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MOTION  PICTURE  NEWS,  Inc. 

729  SEVENTH  AVE.         :-:         NEW  YORK,  N.  Y. 


MOTION    PICTURE 
PROJECTION 


ISAAC   GOLDMANN    COMPANY 
NEW  YORK  CITY 

.^S^SSt*  2  O 


MOTION  PICTURE 
PROJECTION 


An   Elementary    Text-Book 

I 


BY   JAMES   R.   CAMERON 

Technical  Editor 

Exhibitors'  Trade  Review 

International  Cinema  Review 

Educational  Film  Magazine 


SECOND    EDITION 
1921 


Published  by 

THE  THEATRE  SUPPLY   Co. 

124  West  45th  Street 

New  York  City 


MOTION    PICTURE  "  PROJECTION 


GLOSSARY  OF  ELECTRICAL  AND 
MECHANICAL  TERMS 

ACETATE.     A  salt  formed  by  the  action  of  acetic  acid  upon 

a  base. 
ACTUAL  HORSE  POWER.    The  exact  useful  power  given 

out  by  an  engine:  found  by  subtracting  the  power  used  by 

the  machine  itself  from  the  indicated  horse  power. 
ACHROMATIC  LENSES.    The  color  effect  caused  by  the 

chromatic  aberration  of  a  simple  lens  greatly  impairs  its 

usefulness.     This  may  be  overcome  by  combining  into  one 

lens  a  concave  lens  of  flint  glass  and  a  convex  lens  of  crown 

glass. 

ALIGN.    To  place  or  form  in  line. 
ALLOY.     A  mixture  of  two  or  more  metals. 
ALTERNATING  CURRENT.    A  current  that  changes  its 

flow  of  directign  so  many  .times  a  second  according  to  the 

construction  of  the  alternator.    Written  A.  C. 
AMMETER.     An    instrument   used    to    measure    the   flow   of 

amperes. 

AMPERE.     The  unit  of  current  strength. 
AMPERE  HOUR.    The  quantity  of  electricity  passed  by  a 

current  of  one  ampere  in  one  hour. 

One  ampere  flowing  for  one  hour. 

Two  amperes  flowing  for  one-half  hour. 

One-half  ampere  flowing  for  two  hours:  all  equal  one  ampere 

hour. 
ANCHOR  BOLTS.     Bolts  used  for  fastening  machines  to  their 

foundation. 
ANTI-FRICTION    METAL.    A   tin-lead   alloy  like    Babbitt 

metal. 

APERTURE.     An  opening  of  any  description  in  a  partition. 
ARC.    The  arc  between  two  carbon  electrodes  slightly  sepa- 
rated. 
ARC  RECTIFIER.    An  apparatus  used  to  change  A.  C.  to 

D.  C. 
ARMATURE.    A  collection  of  pieces  of  iron  designed  to  be 

acted  on  by  a  magnet. 
ASBESTOS.     A  fibrous  variety  of  ferro-magnesium  silicate; 

is  a  non-conductor  of  heat  and  fireproof. 
ASBESTOS    COVERED    WIRE.    A    cable   containing   very 

fine  strands  of  copper  wire  all  twisted  together  and  covered 

with  an  asbestos  covering.    Used  wherever  heat  is  generated. 


MOTION    PICTURE     PROJECTION 


On  motion  picture  circuits  used  between  the  table  switch  and 
arc  lamp. 

AUTOMATIC.     Self  acting. 

AUTOMATIC  SHUTTER.  The  shutter  covering  the  film 
aperture  in  gate  of  machine  and  controlled  by  the  centrifugal 
or  governor  movement,  is  so  arranged  that  the  shutter  will 
remain  up  so  long  as  the  machine  is  in  motion,  but  should 
the  machine  stop  for  any  reason  then  the  shutter  falls  and 
cuts  off  the  rays  of  light  from  the  film  in  gate.  (A  fire  pre- 
vention device.) 

AUTO  TRANSFORMER.  A  transformer  provided  with  only 
one  coil  instead  of  two.  Part  of  the  coil  being  traversed  by 
the  primary  circuit  and  part  being  traversed  by  the  sec- 
ondary circuit. 

B.  &  S.  W.  G.  Abbreviation  for  Brown  &  Sharpe.  Wire 
Gauge. 

B.  W.  G.     Abbreviation  for  Birmingham  Wire  Gauge. 

B.  X.  Metal  tubing  containing  two  conductors,  each  conductor 
insulated  from  the  other  by  a  rubber  covering,  and  both 
wires  wrapped  with  a  composition  covering  so  as  to  com- 
pletely fill  the  tubing. 

BABBITT  METAL.     An  anti-friction  metal. 

BACK  FOCUS.     Properly  called  working  distance. 

BACK  FOCAL  LENGTH  OF  LENS.  The  distance  from  the 
back  of  the  lens  to  the  film  in  the  gate,  while  the  film  image 
is  in  focus  on  the  screen. 

BALANCE  WHEEL.  A  fly  wheel.  A  wheel  added  to  ma- 
chinery for  the  purpose  of  preventing  too  sudden  variations 
in  speed. 

BALL  &  SOCKET  JOINT.  A  joint  in  which  a  spherical 
object  is  placed  within  a  socket  made  to  fit  it. 

BALL  BEARING.  A  bearing  whose  journal  works  upon  a 
number  of  metal  balls.  Used  to  reduce  friction  to  a  mini- 
mum. 

BED  PIECE.     The  frame  carrying  the  dynamo  or  motor. 

BORE.     The  interior  diameter  of  a  cylinder. 

BRUSH.  A  rod  of  carbon  held  in  a  holder  and  pressed 
against  the  commutator. 

BUSINESS.  Action  by  the  player;  e.  g.,  business  of  shutting 
door. 

BUST.     A  small,  magnified  part  of  a  large  scene. 

CABLE.     An  insulated  electric  conductor. 

CAM  FRICTION.  The  friction  existing  between  the  cam  and 
the  member  connected  to  it. 

CAMERA.  An  expression  used  to  command  the  photographer 
to  begin  taking  the  scene. 


MOTION     PICTURE     PROJECTION 


CANADA  BALSAM.  A  gum  obtained  from  the  Balsam  Fir 
of  Canada.  Used  for  cementing  lenses. 

CARBON.  One  of  the  elements,  exists  in  three  forms,  char- 
coal, graphite  and  diamond.  It  is  used  as  electric  conductor 
for  arc  lamps  and  incandescent  lamp  filaments.  The  car- 
bons used  for  arc  lamps  generally  have  a  central  core  of 
soft  carbon. 

CARRYING  CAPACITY.  The  capacity  of  an  electrical  con- 
ductor to  carry  current  without  overheating. 

CENTIMETER.     Unit  of  length,  0.3937  inch. 

CENTRIFUGAL  FORCE.  The  force  which  draws  a  body 
constrained  to  move  in  a  circular  path,  away  from  the  center 
of  rotation. 

CHANGE  OVER.  The  stopping  of  one  projecting  machine 
and  the  simultaneous  starting  of  a  second  machine  in  order 
to  maintain  an  uninterrupted  picture  on  the  screen  when 
showing  a  multiple-reel  story. 

CHECK  NUT,  generally  called  lock-nut.  A  nut  placed  over 
another  nut  on  same  bolt  to  lock  the  main  nut  in  place. 

CHROMATIC.     Relating  to  color. 

CHROMATIC  ABERRATION.  When  white  light  is  passed 
through  a  spherical  lens,  both  refraction  and  dispersion  (the 
decomposition  of  white  light  into  several  kinds  of  light) 
occur.  This  causes  a  separation  of  the  white  light  into  the 
various  colors  and  causes  images  to  have  colored  edges.  This 
effect  which  is  most  observable  in  condenser  lenses  is  due 
to  the  unequal  refrangibility  of  the  simple  colors. 

CINE.  A  prefix  used  in  description  of  the  motion-picture  art 
or  apparatus. 

CIRCUIT.     The  path  through  which  the  electric  current  flows. 

CIRCUIT  BREAKER.  Any  apparatus  for  opening  or  clos- 
ing a  circuit. 

CIRCUIT-CLOSED.  A  circuit  closed  so  as  to  give  the  cur- 
rent a  continuous  path. 

CIRCUIT,  OPEN.  A  circuit  with  its  continuity  broken,  as  by 
the  opening  of  a  switch. 

CLOSE-UP.  Scene  or  action  taken  with  the  character  close 
to  the  camera. 

COLLODION.  A  solution  of  pyroxylin  (soluble  gun  cotton) 
in  ether.  Used  in  film  cement. 

COMMUTATOR.  That  part  of  a  dynamo  that  changes  the 
direction  of  the  currents. 


10  MOTION    PICTURE     PROJECTION 


COOLING  PLATE.  The  plate  around  the  film  aperture  on 
gate  which  protects  the  gate  itself  from  getting  overheated 
from  the  rays  of  light  from  arc  lamp. 

CONDUCTOR.  Anything  that  will  permit  the  passage  of 
electricity.  A  wire. 

CONDENSERS.  A  lens  or  set  of  lenses  used  to  gather  the 
rays  of  light  from  the  arc  lamp  and  bring  them  to  a  fixed 
point  of  focus  on  aperture  in  gate. 

The  lens  combination  which  deflects  the  diverging  rays  of 
the  luminant  into  the  objective. 

Collector  Lens.    The  lens  next  to  the  source  of  light. 
Converging  Lens.     The  lens  nearest  the  objective. 
Middle  Lens.     Of  a  three-lens   combination,  the  lens   lying 
between  the  collector  lens  and  the  converging  lens. 

CONDUIT.  A  metal  pipe  through  which  electrical  conductors 
are  run. 

CONTACT,  ELECTRIC.  A  contact  between  two  conductors 
giving  a  continuous  path  for  the  current. 

CONSTANT  LOAD.  A  load  whose  pressure  is  steady  and  in- 
variable. 

CONTINUOUS.  Uninterrupted  without  break,  or  interrup- 
tion. 

CONVERTER.  An  electric  machine  or  apparatus  for  chang- 
ing the  potential  difference  of  an  electrical  circuit. 

CORROSION.  Chemical  action  which  causes  destruction  of  a 
metal,  usually  by  oxidation  or  rusting. 

CORRUGATED.  Formed  with  a  surface  consisting  of  alter- 
nate valleys  and  ridges. 

COULOMB.  The  practical  unit  of  quantity  of  electricity.  It 
is  the  quantity  passed  by  a  current  of  one  ampere  intensity 
in  one  second. 

CRATER.  The  depression  that  forms  in  the  positive  carbon 
of  a  voltaic  arc. 

CURRENT  FREQUENCY.  The  number  of  times  alternating 
current  changes  its  flow  of  direction  a  second.  The  changes 
are  called  cycles. 

CUT-BACK.     Scenes  which  are  returns  to  previous  action. 

CUT-IN.  Anything  inserted  in  a  scene  which  breaks  its  con- 
tinuity. 

CUTTING.  Editing  a  picture  by  elimination  of  useless  or 
unacceptable  film. 

DEVELOPING.  Making  visible  the  latent  image  in  an  ex- 
posed film. 

DIRECT  CURRENT.  A  current  that  flows  in  the  one  direc- 
tion- Written  D.  C. 


MOTION     PICTURE     PROJECTION  11 

DIMMER.  An  adjustable  choking  coil  used  to  regulate  the 
intensity  of  electric  incandescent  lamps. 

DIRECTOR.  The  person  who  directs  the  actual  production 
of  the  photoplay. 

DISSOLVE.     The  gradual  transition  of  one  scene  into  another. 

DOUBLE  EXPOSURE.  The  exposure  of  a  negative  film  in 
a  camera  twice  before  development. 

DOUBLE  PRINTING.  The  exposure  of  a  sensitive  film 
under  two  negatives  prior  to  development. 

DOUSER.  The  manually  operated  door  in  the  projecting 
machine  which  intercepts  the  light  before  it  reaches  the  film. 

DUPE.     A  negative  made  from  a  positive. 

DUPLEX.    Double;  working  in  two  ways  at  once. 

DYNAMOS.  A  machine  driven  by  power  used  to  convert  me- 
chanical energy  into  electrical  energy. 

E.  M.  F.     Abbreviation  for  electric-motive  force. 

ECONOMIZER.     A  step-down  transformer. 

EFFECTIVE  APERTURE.  The  largest  diameter  of  a  lens 
available  under  the  conditions  considered. 

ELECTRICITY.  An  unknown  power;  a  powerful  physical 
agent  which  manifests  itself  mainly  by  attraction  and  repul- 
sions, also  by  luminous  and  heating  effects,  by  violent  com- 
motions, by  chemical  decompositions  and  many  other  phe- 
nomena. 

ELECTRODE.     The  terminal  of  an  open  electric  circuit. 

EQUIVALENT  FOCUS.  The  distance  from  a  point  half  way 
between  the  back  and  front  combination  of  lenses  to  the 
film  in  the  gate  while  picture  is  in  focus  on  screen. 

Can  be  obtained  by  measuring  the  distance  between  the 
front  and  back  combination  then  dividing  by  two  and  adding 
the  result  to  the  back  focal  length.  (Written  E.  F.) 

The  equivalent  focus  of  a  plurality  of  lenses  in  combina- 
tion is  the  focal  length  of  a  simple  thin  lens  which  will  under 
all  conditions  form  an  image  having  the  same  magnification 
as  will  the  given  lens  combination. 

EXHAUST  FAN.    An  air  propeller  used  to  create  a  vacuum. 

EXTERIOR.     A  scene  supposed  to  be  taken  out  of  doors. 

FADE-IN.  The  gradual  appearance  of  the  picture  from  dark- 
ness to  full  screen  brilliancy. 

FADE-OUT.  The  gradual  disappearance  of  the  screen- 
picture  into  blackness.  (The  reverse  of  fade-in.) 

FEATURE.     A  pictured  story,  a  plurality  of  reels  in  length. 

FIRE  TRAP.  An  arrangement  of  rollers  on  the  upper  and 
lower  magazines  through  which  the  film  is  fed,  used  to  pre- 
vent the  flame,  in  case  of  fire,  from  entering  the  magazines. 

FIXING.     Making  permanent  the  developed  image  in  a  film. 


12  MOTION    PICTURE     PROJECTION 


FLAT.     A  bit  of  painted  canvas,  or  the  like. 

FLASH.  A  short  scene,  usually  not  more  than  three  to  five 
feet  of  film. 

FLASH-BACK.     A  very  short  cut-back. 

FOCAL.     Pertaining  or  belonging  to  a  focus. 

FOCUS.  The  point  of  concentration.  When  rays  reflected 
from  all  points  meet  or  concur. 

FOOTAGE.     Film  length  measured  in  feet. 

FLICKER  SHUTTER.  A  revolving  shutter  on  head  of  ma- 
chine just  in  front  of  the  projection  lens,  its  use  being  to 
cut  off  the  rays  of  light  from  screen  while  the  film  is  in  mo- 
tion in  gate. 

FRAME  (verb).  To  bring  a  frame  into  register  with  the 
aperture  during  the  period  of  rest. 

FRAME  (noun).  A  single  picture  of  the  series  on  a  motion- 
picture  film. 

FRAME  LINE.     The  dividing  line  between  two  frames. 

FRAMING  DEVICE.  An  attachment  on  the  machine  which 
allows  the  operator  to  frame  the  picture  on  screen. 

FUSE.  A  short  length  of  wire  of  a  given  fusable  point  in- 
troduced into  the  electrical  circuit. 

FUSING  POINT.  The  temperature  at  which  metals  melt  and 
become  liquid. 

GENERATOR.  An  apparatus  for  maintaining  an  electrical 
current. 

GOVERNOR  MOVEMENT.  The  movement  that  works  the 
automatic  shutter,  works  by  centrifugal  force. 

GRAPHITE.     A  soft  form  of  carbon,  used  as  a  lubricant. 

GROUND.  The  contact  of  an  electrical  conductor  with  the 
earth,  or  with  some  other  conductor  not  in  the  circuit. 

HORSE  POWER.  A  unit  of  rate  of  work.  Equal  to  the  rais- 
ing of  33,000  pounds,  one  foot  in  one  minute;  equal  to  746 
watts. 

INDUCTION.  The  property  of  a  charged  body  on  A.  C.  to 
charge  a  neighboring  body  running  parallel  to  it  without  any 
tangible  form  of  connection. 

INDUCTOR.     A  step-down  transformer. 

IMPEDANCE.  Is  to  an  A.  C.  circuit  what  resistance  is  to  a 
D.  C.  circuit. 

INSULATING  TAPE.  A  prepared  tape  to  cover  the  ends 
of  bared  wire. 

INTERMITTENT  MOVEMENT.  The  movement  that  drives 
the  intermittent  sprocket,  generally  a  four-to-one  movement. 

INTERMITTENT  SPROCKET-  The  sprocket  which  engages 
the  film  to  give  it  intermittent  movement  at  the  picture 
aperture. 


MOTION    PICTURE     PROJECTION  13 


INSERT.  Any  photographic  matter,  without  action,  in  the 
film. 

INTERIOR.  Any  scene  supposed  to  be  taken  inside  a  build- 
ing. 

IRIS.     An  adjustable  lens  diaphragm. 

IRISING.  Gradually  narrowing  the  field  of  vision  by  a  me- 
chanical device  on  the  camera. 

JOINING.  Splicing  into  a  continuous  strip  (usually  1,000 
feet)  the  separate  scenes,  titles,  etc.,  of  a  picture. 

KILOWATT.    Equal  to  1,000  watts. 

LAMINATED.     Made  up  of  a  number  of  thin  sheets. 

LANTERN  PICTURE.  A  still  picture  projected  on  a  screen 
by  means  of  an  optical  lantern  or  stereopticon. 

LANTERN  SLIDE  (see  slide).  The  transparent  picture 
from  which  a  lantern  picture  is  projected. 

LEADERS.  That  piece  of  blank  film  attached  to  the  begin- 
ning of  the  picture  series. 

LENS.  A  lens  may  be  defined  as  a  piece  of  glass  or  other 
transparent  substance  with  one  or  both  sides  curved.  Both 
sides  may  be  curved,  or  one  curved  and  other  flat. 

The  object  of  the  lens  is  to  change  the  direction  of  rays 
of  light  and  thus  magnify  objects  or  otherwise  modify  vision. 
Lenses  may  be  classed  as: 

Double  convex  Double  concave 

Piano  convex  Piano  concave 

Concavo  convex  Convexo  concave 

The  focus  of  a  lens  is  the  point  where  the  refracted  rays 
meet. 

LIGHT  BEAM.     A  bundle  of  light  rays. 

LIGHT  RAY.     A  thin  line  of  light. 

LOCATION.  Any  place  selected  for  the  action  of  an  outdoor 
scene. 

LOST  MOTION.  Motion  in  a  part  of  machine  that  produces 
no  useful  results. 

LUBRICANT.  An  oil  used  to  diminish  friction  in  the  work- 
ing parts  of  machinery. 

LUG.     A  wire  terminal. 

MAGAZINE  VALVE.  The  film  opening  in  the  magazine  of 
a  motion-picture  projector. 

MAN  POWER.     Equal  to  one-tenth  of  a  horse  power. 

MASKS.  Opaque  plates  of  various  sizes  and  shapes  used  in 
the  camera  to  protect  parts  of  the  negative  from  exposure. 

MICA.  A  mineral  more  or  less  transparent  and  used  for  in- 
sulating. 

MIL.     Unit  of  length. 

MIL,  CIRCULAR.     Unit  of  area. 


14  MOTION     PICTURE     PROJECTION 


MOTION-PICTURE.  The  synthesis  of  a  series  of  related 
picture  elements,  usually  of  an  object  in  motion. 

MOTION-PICTURE  FILM.  The  ribbon  upon  which  the 
series  of  related  picture  elements  is  recorded. 

MOTION-PICTURE  PROJECTOR.  An  optical  lantern 
equipped  with  mechanisms  for  suitably  moving  motion-picture 
film  across  the  projected  light. 

MOTOR  GENERATOR.     A  motor  connected  to  a  generator. 

MOTOR  REGULATOR.  An  adjustable  rheostat  used  to  reg- 
ulate the  speed  of  the  motor. 

MOVIES.     Motion  pictures. 

MULTIPLE.  Multiple  connection  is  when  each  lamp  draws 
its  supply  direct  from  the  main  and  is  not  depending  on  any 
other  lamp  or  set  of  lamps  for  supply. 

MULTIPLE-REEL.  A  photoplay  of  more  than  a  thousand 
feet  of  film  in  length. 

NEGATIVE.  The  opposite  to  positive;  the  pole  to  which  the 
current  is  supposed  to  flow. 

NEGATIVE.  The  developed  film,  after  being  exposed  in  a 
camera. 

NEGATIVE  STOCK.  Light  sensitive  film  intended  for 
motion-picture  camera  use. 

NON  CONDUCTOR.  Any  material  that  does  not  conduct 
electricity. 

OBJECTIVE.  The  picture-forming  member  (lens)  of  the 
optical  system.  The  objective  lens  of  a  moving  picture 
machine  generally  consists  of  four  lenses,  two  in  the  front 
combination  and  two  in  the  rear.  The  two  lenses  in  the 
front  are  cemented  together  with  Canada  Balsam  and  called 
the  compound  lens.  The  back  combination  consists  of  two 
lenses  separated  by  a  metal  ring,  called  the  duplex  lens. 

The  convex  or  greatest  convex  side  of  a  lens  always  faces 
the  screen. 

OHM.     The  unit  of  electrical  resistance. 

OSCILLATION.  A  moving  backward  and  forward;  swinging 
like  a  pendulum. 

OPTIENCE.  A  collection  of  persons  assembled  to  see 
motion  pictures. 

PAM.     Contraction  for  panorama. 

PANORAM.  The  act  of,  or  device  for,  turning  a  motion- 
picture  camera  horizontally,  to  photograph  a  moving  object, 
or  to  embrace  a  wide  angle  of  view. 

PHOTOPLAY.     A  story  in  motion  pictures. 

POLARITY.  Pertaining  to  the  two  opposite  poles  of  a  cir- 
cuit; the  positive  and  negative. 

POLYPHASE.     More  than  one  phase,  multiphase. 


MOTION    PICTURE     PROJECTION  15 


POSITIVE.  The  developed  film,  after  being  printed  through 
a  negative. 

POSITIVE  STOCK.  The  light-sensitive  film  intended  to  be 
printed  upon  through  a  negative. 

PRE-RELEASE.  A  picture  not  yet  released  for  public 
showing. 

PRESSURE,  ELECTRIC.     Electric  motive  force,  voltage. 

PRIMARY  COIL.  The  coil  of  a  transformer,  connected  to  the 
source  of  electrical  supply. 

PRIMARY  COLORS.    Red,  yellow,  blue. 

PRIMARY  POWERS.  Water  power,  wind  power,  tide  power, 
power  of  combustion,  power  of  vital  action. 

PRINT.    Same  as  "positive." 

PRODUCER.     The  maker  of  photoplays. 

PROGRAM.     The  complete  show  for  a  single  optience. 

PROJECTION  DISTANCE.  The  distance  between  the  screen 
and  the  objective  of  a  stereopticon  lantern  or  motion- 
picture  projecting  machine. 

PROJECTING  LENS.     Properly  called  projection  objective. 

PROJECTION  OBJECTIVE.  The  objective  which  forms  an 
image  of  the  lantern  slide  or  film,  upon  the  screen. 

PROPS.  Contraction  of  properties.  Objects  used  as  acces- 
sories in  a  play. 

RACING  OF  MOTORS.  The  rapid  acceleration  of  speed  of 
a  motor  when  the  load  upon  it  is  removed. 

REEL.  An  arbitrary  unit  of  linear  measure  for  film — approx- 
imately a  thousand  feet. 

REEL.     The  metal  spool  upon  which  the  film  is  wound. 

REFLECTION.  The  change  of  direction  experienced  by  a 
ray  of  light  when  it  strikes  a  surface  and  is  thrown  back 
or  reflected,.  Light  is  reflected  according  to  two  laws. 

(a)  The  angle  of  reflection  is  equal  to  the  angle  of  inci- 
dence. 

(b)  The  incident  and  the  reflected  rays  are  both  in  the 
same  plane  which   is  perpendicular  to   the   reflecting 
surface. 

REFRACTION.  The  change  of  direction  which  a  ray  of 
light  undergoes  upon  entering  obliquely  a  medium  of  differ- 
ent density  from  that  through  which  it  has  been  passing.  In 
this  case  the  following  laws  obtain: 

(a)  Light  is  refracted  whenever  it  passes  obliquely  from 
one  medium  to  another  of  different  optical  density. 

(b)  The  index  of  refraction  'for  a  given  substance  is  a  con- 
stant quantity  whatever  be  the  angle  of  incidence. 


16  MOTION    PICTURE     PROJECTION 


(c)  The  refracted  ray  lies  in  the  plane  of  the  incident  ray 
and  the  normal. 

(d)  Light  rays   are   bent  toward   the  normal  when   they 
enter  a  more  refracted  medium  and  from  the  normal 
when  they  enter  a  less  refracted  medium. 

REGISTER.     A  term  denoting  facial  expression  of  emotions. 

RELEASE.     The  publication  of  a  photoplay. 

RETAKE.     Rephotographing  a  scene. 

REWIND.  The  process  of  reversing  the  winding  of  a  film, 
usually  so  that  the  end  to  be  first  projected  shall  lie  on  the 
outside  of  the  roll. 

RE  WINDER.  The  mechanism  Vy  which  rewinding  is  accom- 
plished. 

RESISTANCE  BOX.  A  box  filled  with  resistance  coils  con- 
nected in  series. 

RHEOSTAT.  'An  instrument  used  to  offer  resistance  to  the 
flow  of  current.  Made  of  a  number  of  metal  coils  connected 
in  series  and  mounted  on  a  frame. 

RUBBER  COVERED  WIRE.  A  cable  either  solid  or  strand- 
ed with  a  rubber  covering  and  an  outer  protective  covering 
of  cotton  braid.  Used  for  mains  for  motion  picture  work. 

SCENE.     The  action  taken  at  a  single  camera  setting. 

SCENARIO.  A  general  description  of  the  action  of  a  pro- 
posed photoplay. 

SCREEN.  The  surface  upon  which  a  picture  is  optically  pro- 
jected. 

SECONDARY  COIL.  The  coil  of  a  transformer  in  which  the 
current  is  induced,  connected  to  the  lamp. 

SERIES.  An  electrical  connection  where  lamps  are  connected 
so  that  they  depend  on  each  other  for  supply,  the  current 
passing  through  each  lamp  successively. 

SHOOTING  A  SCENE.     Photographing  the  scene. 

SHORT  CIRCUIT.  Two  wires  of  opposite  polarity  coming 
in  contact  with  each  other  without  any  controlling  device. 

SHUTTER.     The  obscuring  device,  usually  a  revolving  seg- 
mental  disc,  employed  to  intercept  the  light  during  the  move- 
ment of  the  film  in  motion-picture  apparatus. 
Shutter — Working  Blade   (also  variously  known  as  the  cut- 
ting blade,  obscuring  blade,  main  blade,  master  blade  or 
travel  blade).     That  segment  which   intercepts   the  light 
during  the  movement  of  the  film  at  the  picture  aperture. 
Shutter — Intercepting    Blade     (also    known    as    the    flicker 
blade).     That  segment  which  intercepts  the  light  one  or 
more  times  during  the  rest  or  projection  period  of  the  film 
to  eliminate  flicker. 

SIXTY  CYCLE  A.  C.     This  is  when  every  part  of  the  circuit 


MOTION     PICTURE     PROJECTION  17 

is  60  times  positive  and  60  times  negative  every  second.  The 
current  changes  its  flow  of  direction  60  times  a  second. 

SINGLE  PHASE.  Using  only  two  wires  and  one  E.  M.  F. 
sometimes  called  monophase  or  uniphase. 

SINGLE  PICTURE  CRANK  (sometimes  referred  to  as  trick 
spindle).  That  spindle  and  crank  on  a  motion-picture 
camera  which  makes  one  exposure  at  each  complete  revo- 
lution. 

SLIDE  (Stereo  Slide).  The  transparent  picture  from  which 
a  screen  still  is  projected. 

SLIDING  FRICTION.  The  friction  existing  between  two 
bodies  in  sliding  contact  with  each  other. 

SPEED  REGULATOR.  An  attachment  on  machine  (gen- 
erally a  friction  disc  arrangement)  used  to  regulate  the 
speed  of  machine  (not  the  speed  of  motor). 

SPHERICAL  ABERRATION.  The  reflected  rays  of  con- 
cave spherical  mirrors  do  not  meet  exactly  at  the  same  point. 
This  is  called  spherical  aberration. 

SPLICING.     Joining  the  ends  of  film  by  cementing. 

SPLIT  REEL.  A  reel  having  two  or  more  picture  subjects 
thereon. 

SPOT.  The  illuminated  area  on  the  aperture  plate  of  a 
motion-picture  projector. 

SPROCKET.  The  revolvable  toothed  member  which  engages 
the  perforations  in  the  film. 

STAGE  CABLE.  A  cable  containing  twin  conductors  each 
insulated  from  the  other  and  the  whole  thing  covered  with  a 
composition  covering.  Used  for  temporary  purposes. 

STEP-DOWN  TRANSFORMER.  A  transformer  that  steps 
down  the  voltage  and  raises  the  amperage. 

STEP-UP  TRANSFORMER.  A  transformer  that  steps  up 
the  voltage  and  lowers  the  amperage. 

STEREOPTICON.  A  lantern  for  projecting  transparent  pic- 
tures, i.  e.,  lantern  slides,  often  a  double  lantern  for  dis- 
solving. 

STILL.     A  picture  from  a  single  negative. 

STRIKING  THE  ARC.  The  act  of  bringing  the  carbons  of 
an  arc  lamp  together,  and  immediately  separating  them,  thus 
establishing  the  arc. 

SWITCH  BOARD.  A  board  to  which  wires  are  led  connecting 
with  cross  bars  or  switches. 

SWITCH,  DOUBLE  POLE.  A  heavy  switch  which  connects 
and  disconnects  two  leads  simultaneously. 

SWITCH,  KNIFE.  A  switch  with  knife-like  blades  used  on 
circuits  carrying  high  amperage. 


18  MOTION    PICTURE     PROJECTION 


SWITCH,  SNAP.  A  small  switch  made  to  give  a  sharp  break 
used  on  home  lighting  circuits. 

SWITCH,  THREE  WAY.  A  switch  so  constructed  that  by 
turning  its  handle,  connection  can  be  made  from  one  lead  to 
either  of  two  other  leads,  and  also  so  that  connection  can  be 
completely  cut  off. 

TAKE-UP  (noun).  The  mechanism  which  receives  and  winds 
the  film  after  it  passes  the  picture  aperature.  Generally 
consists  of  a  split  pulley  and  tension  spring,  its  use  is  to 
drive  and  control  the  speed  and  tension  of  the  reel  taking 
up  the  film  in  lower  magazine. 

TAKE-UP  (verb).  Winding  up  the  film  after  it  passes  the 
picture  aperture. 

TENSION  SPRINGS.  On  gate  of  machine,  used  to  give  the 
proper  tension  to  film  while  passing  aperture. 

THREE  WIRE  SYSTEM.  A  system  of  distribution  of  elec- 
tric current  where  three  wires  instead  of  two  sets  of  two 
wires  are  used.  The  middle  or  neutral  wire  acts  as  positive 
wire  for  the  negative,  and  as  negative  wire  for  the  positive. 
The  advantage  of  the  system  is  the  saving  of  copper. 

THREE  PHASE.  A  system  of  electrical  distribution  making 
use  of  three  separate  currents.  These  currents  may  be  super- 
imposed and  generally  only  three  wires  are  used  in  this  trans- 
mission. 

THROW.  Projection  distance.  Distance  from  front  com- 
bination of  lens  to  screen. 

TILT.  The  act  of,  or  device  for,  moving  a  camera  vertically 
while  in  use. 

TINTING.     Coloring  a  film  by  dyeing  the  gelatine  side  of  it. 

TONING.  Coloring  a  film  by  chemical  action  on  the  silver 
image. 

TRAILER.  That  piece  of  blank  film  attached  to  the  end  of 
a  picture  series. 

TRANSFORMER.  An  apparatus  used  on  alternating  cur- 
rent systems  to  raise  or  lower  the  voltage. 

TRANSVERTER.  A  motor  generator  set,  an  A.  C.  motor 
connected  to  a  D.  C.  generator. 

TRICK  CRANK.  A  camera  crank  giving  a  single  exposure 
for  each  turn. 

TRICK-PICTURE.  -A  picture  in  which  unnatural  action  ap- 
pears. 

TWO  PHASE.  An  A.  C.  system  of  electrical  distribution 
making  use  of  two  currents  of  different  phase.  Can  be  ar- 
ranged with  either  8  or  4  wires. 

VISION.     A  new  subject   introduced  into  the  main   picture, 


MOTION    PICTURE     PROJECTION 


19 


by  the  gradual  fading-in  and  fading-out  of  the  new  subject, 

as,  for  example,  to  visualize  a  thought. 
VOLTAGE.     Electric  motive  force  or  pressure. 
VOLTMETER.     An  instrument  used  to  measure  the  electric 

pressure. 
WATT.     The   practical   unit   of   electrical   power.     Equal   to 

amperes  times  volts. 

WATT  HOUR.    Amount  of  watts  times  length  of  hours. 
WORKING   DISTANCE.     The    distance   from   the   principal 

focus  of  a  lens  to  its  nearest  face;  e.  g.,  the  distance  from 

the  slide  or  film  to  the  nearest  lens  of  the  objective. 


20  MOTION     PICTURE     PROJECTION 


MOTION    PICTURE    STANDARDS 

The  following  have  been  adopted  as  standards  by 
the  Society  of  Motion-Picture  Engineers,  and  are 
promulgated  to  encourage  uniformity  and  standard 
practice  throughout  the  Industry  as  a  whole.  Their 
early  universal  adoption  will  save  the  industry  a 
great  deal  of  present  annoyance  and  monetary  loss. 

FILM  SPEED.  A  film  movement  of  sixty  feet  per  minute 
through  motion-picture  mechanisms  shall  be  considered  as 
standard  speed. 

FRAME  LINE.  The  dividing  line  between  pictures  on 
motion-picture  film  shall  lie  exactly  midway  between  the 
marginal  perforations. 

INTERMITTENT  GEAR  RATIO.  The  movement  of  the  in- 
termittent gear  shall  be  expressed  in  degrees  of  rotation 
during  which  the  pin  of  the  driver  is  in  contact  with  the  slot 
of  the  driven  gear.  For  example,  a  gear  in  which  the  pin  is 
engaged  with  the  slot  for  one-quarter  of  a  revolution  of  the 
driver  shall  be  called  a  90-degree  movement;  that  in  which 
the  pin  is  engaged  with  the  slot  for  one-sixth  of  a  revolution 
shall  be  called  a  60-degree  movement,  etc. 

LANTERN  SLIDE  MAT  OPENING.  A  standard  opening  in 
mats  of  lantern  slides  for  use  in  conjunction  with  motion 
pictures  shall  be  3  inches  wide  by  2*4  inches  high. 

THUMB  MARK.  The  thumb  mark  spot  on  a  lantern  slide 
shall  be  located  in  the  lower  left-hand  corner  next  the  reader 
when  the  slide  is  held  so  as  to  be  read  against  a  light. 

LANTERN  STRIP.  A  red  binding  strip  to  be  used  on  the 
lower  edge  of  the  lantern  slide. 

PICTURE  APERTURE.  The  standard  film  picture  aperture 
in  a  projecting  machine  shall  be  0.906  inch  wide  and  0.6795 
inch  high,  namely,  29/32"  and  87/128". 

PROJECTION  ANGLE.  The  maximum  permissible  angle  in 
picture  projection  shall  not  exceed  twelve  degrees  (12°) 
from  a  perpendicular  to  the  screen  surface. 

PROJECTION  LENS  FOCI.  The  focus  of  motion-picture 
projection  lenses  shall  increase  in  ^4"  steps  to  8  inches  and 
from  8  to  9  in  ^-inch  steps. 

PROJECTION  LENS  MOUNTING.  Picture  projecting 
lenses  shall  be  so  mounted  that  the  light  from  the  film 


MOTION     PICTURE     PROJECTION  21 


picture  aperture  shall  have  an  uninterrupted  full  path  to  the 
rear  component  of  the  lens. 

PROJECTING  LENS  HEIGHT.  The  standard  height  from 
the  floor  to  the  center  of  the  projecting  lens  of  a  motion- 
picture  machine  shall  be  48  inches. 

PROJECTION  LENS  OPENING.  The  diameter  of  unit 
opening  for  projecting  lens  holder  shall  be  1  15/16  inch. 

PROJECTION  OBJECTIVES.  Shall  have  the  equivalent 
focal  length  marked  thereon  in  inches  and  quarters  and 
halves  of  an  inch,  in  decimals,  with  a  plus  (-f)  or  minus  ( — ) 
tolerance  not  to  exceed  1  per  cent,  of  the  designated  equiv- 
alent focal  length  also  marked  by  the  proper  sign  following 
the  figure. 

REEL.  The  approved  standard  reel  shall  be  10  inches  in 
diameter;  iy2  inches  inside  width;  with  5/16-inch  center 
hole,  with  a  key-way  %"  by  %"  extending  all  the  way 
through;  a  2-inch  hub;  and  a  permissible  flange  wabble  of 
not  more  than  1/16-inch. 

STANDARD  PICTURE  FILM.  Shall  be  one  and  one-third 
inches  wide,  and  carry  a  picture  for  each  four  perforations- 
the  vertical  position  of  the  picture  being  longitudinal  of 
the  film. 

STANDARD  REEL  FILM.  Shall  have  black  film  leaders, 
with  tinted  (red,  green  or  blue)  trailers;  should  have  mark- 
ing thereon  embossed  rather  than  punched  in  the  film;  and 
each  reel  of  a  multiple-reel  story  should  end  with  a  title,  and 
the  next  reel  begin  with  the  same  title. 

TAKE-UP  PULL.  The  take-up  pull  on  film  shall  not  exceed 
15  ounces  at  the  periphery  of  a  10-inch  reel  or  16  ounces  on 
a  (11-inch)  reel. 


22  MOTION     PICTURE     PROJECTION 


'A   Pocket   Reference  Book 

FOR 

Managers  and  Projectionists' 

By  JAMES  R.  CAMERON 


Price  One  Dollar 
THEATRE  SUPPLY  COMPANY 

124  WEST  45xn  STREET  NEW  YORK  CITY 


MOTION    PICTURE     PROJECTION  23 


ELECTRICITY 

No  one  knows  exactly  what  electricity  is,  we  do 
not  even  know  what  it  consists  of,  we  do  know  that 
electricity  and  magnetism  are  one  and  the  same. 
Electricity  is  not  matter  nor  yet  is  it  energy,  al- 
though it  is  a  means  of  transmitting  energy,  and  we 
know  how  to  handle  this  force  for  this  purpose. 

It  is  an  undeniable  fact  that  energy  cannot  be 
created  nor  can  it  be  destroyed,  but  we  can  convert 
one  kind  of  energy  into  energy  of  another  kind.  For 
example,  should  we  light  a  fire  under  a  vessel  con- 
taining water  we  will  convert  the  heat  energy  from 
the  coals  to  steam  energy  in  the  vessel  containing 
the  water,  and  we  could  again  change  this  steam 
energy  into  mechanical  energy,  as  is  done  with  the 
locomotive. 

It  is  also  possible  to  convert  mechanical  energy 
into  electrical  energy,  so  by  connecting  the  mechani- 
cal energy  created  by  the  steam  to  a  dynamo  we 
would  produce  electrical  energy. 

It  is  also  possible  to  convert  electrical  energy  into 
mechanical  energy.  A  motor  is  used  for  this  purpose. 

The  word  dynamo  is  used  to  designate  a  machine 
which  produces  direct  current  as  distinguished  from 
the  alternator  or  generator  which  produces  alternat- 
ing current.  A  dynamo  does  not  create  electricity 
but  produces  an  induced  electric-motive  force  which 
causes  a  current  of  electricity  to  flow  through  a 
circuit  of  conductors  in  much  the  same  manner  as  a 
pump  causes  water  to  flow  through  a  pipe.  The 
point  to  be  settled  in  the  minds  of  those  taking  up 


24  MOTION    PICTURE    PROJECTION 

electricity  is  that  the  dynamo  merely  sets  into  mo- 
tion something  already  existing,  by  generating  suf- 
ficient pressure  to  overcome  the  resistance  to  its 
movement. 

Although  we  speak  of  alternating  and  direct  cur- 
rent, it  should  be  clearly  understood  that  it  is  im- 
possible to  get  a  continuous  current  with  a  dynamo. 
The  current  is  really  a  pulsating  one,  but  the  pulsa- 
tions are  so  small  and  follow  each  other  so  quickly 
that  the  current  is  practically  continuous. 

Electromotive  Force.  When  a  difference  of  elec- 
trical potential  exists  between  two  points,  there  is 
said  to  exist  an  electromotive  force,  or  tendency  to 
cause  a  current  to  flow  from  one  point  to  the  other. 
This  electromotive  force  is  analogous  to  the  pressure, 
caused  by  a  difference  in  level  of  two  bodies  of  water 
connected  by  a  pipe.  The  pressure  tends  to  force 
the  water  through  the  pipe,  and  the  electromotive 
force  tends  to  cause  an  electric  current  to  flow. 

Electromotive  force  is  commonly  designated  by 
the  letters  E.  M.  F.  or  simply  E.  It  is  also  referred 
to  as  pressure  or  voltage. 

Current.  A  current  of  electricity  flows  when  two 
points,  at  a  difference  of  potential,  are  connected  by 
a  wire,  or  when  the  circuit  is  otherwise  completed. 
Similarly,  water  flows  from  a  high  level  to  a  lower 
one,  when  a  path  is  provided.  In  either  case  the  flow 
can  take  place  only  when  the  path  exists.  Hence 
to  produce  a  current  it  is  necessary  to  have  an  elec- 
tromotive force  and  a  closed  circuit.  The  current 
continues  to  flow  only  as  long  as  the  electromotive 
force  and  closed  circuit  exists. 

The  strength  of  a  current  in  a  conductor  is  defined 


MOTION    PICTURE     PROJECTION  25 

as  the  quantity  of  electricity  which  passes  any  point 
in  the  circuit  in  a  unit  of  time.  Current  is  desig- 
nated by  the  letter  C  or  /. 

Resistance.  Resistance  is  that  property  of  mat- 
ter, in  virtue  of  which  bodies  oppose  or  resist  the 
free  flow  of  electricity.  Water  passes  with  difficulty 
through  a  small  pipe  of  great  length  or  through  a 
pipe  filled  with  stones  or  sand,  but  very  readily 
through  a  large,  clear  pipe  of  short  length.  Like- 
wise, a  small  wire  of  considerable  length  and  made 
of  poor  conducting  material  offers  great  resistance 
to  the  passage  of  electricity,  but  a  good  conductor 
of  short  length  and  large  cross-section  offers  very 
little  resistance. 

Resistance  is  designated  by  the  letter  R. 

Volt,  Ampere  and  Ohm.  The  volt  is  the  practical 
unit  of  electromotive  force. 

The  ampere  is  the  practical  unit  of  current. 

The  ohm  is  the  practical  unit  of  electrical  resist- 
ance. The  microhm  is  one  millionth  of  an  ohm,  and 
the  megohm  is  one  million  ohms. 

The  International  ohm,  as  nearly  as  known,  is  the 
resistance  of  a  uniform  column  of  mercury  106.3 
centimeters  in  length  by  one  square  milimeter  in 
cross-section  at  a  temperature  of  zero  centigrade. 

The  ampere  is  the  strength  of  current  which,  when 
pased  through  a  solution  of  silver  nitrate,  under  suit- 
able conditions,  deposits  silver  at  the  rate  of  .001118 
gram  per  second. 

The  volt  is  equal  to  the  E.  M.  F.  which,  when 
applied  to  a  conductor  having  a  resistance  of  one 
ohm,  will  produce  in  it  a  current  of  one  ampere. 

All  substances  resist  the  passage  of  electricity,  but 


26  MOTION    PICTURE     PROJECTION 

the  resistance  offered  by  some  is  very  much  greater 
than  that  offered  by  others.  Metals  have  by  far  the 
least  resistance,  and  of  these,  silver  possesses  the 
least  of  any.  In  other  words,  silver  is  the  best  con- 
ductor. If  the  temperature  remains  the  same,  the 
resistance  of  a  conductor  is  not  affected  by  the  cur- 
rent passing  through  it.  A  current  of  ten,  twenty 
or  any  number  of  amperes  may  pass  through  a  cir- 
cuit, but  its  resistance  will  be  unchanged  with  con- 
stant temperature.  Resistance  is  affected  by  the 
temperature  and  also  by  the  degree  of  hardness. 
Annealing  decreases  the  resistance  of  a  metal. 

Conductance  is  the  inverse  of  resistance;  that  is, 
if  a  conductor  has  a  resistance  of  R  ohms,  its  con- 

1 

ductance  is  equal  to  — . 
R 

Resistance  Proportional  to  Length.  The  resis- 
tance of  a  conductor  is  directly  proportional  to 
its  length.  Hence,  if  the  length  of  a  conductor  is 
doubled,  the  resistance  is  doubled,  or  if  the  length  is 
divided,  say  into  three  equal  parts,  then  the  resis- 
tance of  each  part  is  one-third  the  total  resistance. 

Resistance  Inversely  Proportional  to  Cross-Sec- 
tion. The  resistance  of  a  conductor  is  inversely 
proportional  to  its  cross-sectional  area.  Hence  the 
greater  the  cross-section  of  a  wire  the  less  is  its 
resistance.  Therefore,  if  two  wires  have  the  same 
length,  but  one  has  a  cross-section  three  times  that 
of  the  other,  the  resistance  of  the  former  is  one-third 
that  of  the  latter. 

As  the  area  of  a  circle  is  proportional  to  the 
square  of  its  diameter,  it  follows  that  the  resistances 


MOTION     PICTURE     PROJECTION  27 

of  round  conductors  are  inversely  proportional  to 
the  squares  of  their  diameters. 

Specific  Resistance.  The  specific  resistance  of  a 
substance  is  the  resistance  of  a  portion  of  that  sub- 
stance of  unit  length  and  unit  cross-section  at  a 
standard  temperature.  The  units  commonly  used  are 
the  centimeter  or  the  inch,  and  the  temperature  that 
of  melting  ice.  The  specific  resistance  may  there- 
fore be  said  to  be  the  resistance  (usually  stated  in 
microhms)  of  a  centimeter  cube  or  of  an  inch  cube 
at  the  temperature  of  melting  ice.  If  the  specific 
resistances  of  two  substances  are  known,  then  their 
related  resistance  is  given  by  the  ratio  of  the  specific 
resistance. 

Calculation  of  Resistance.  It  is  evident  that  re- 
sistance varies  directly  as  the  length,  inversely  as 
the  cross-sectional  area,  and  depends  upon  the  spe- 
cific resistance  of  the  material. 

If  a  circuit  is  made  up  of  several  different  mate- 
rials joined  in  series  with  each  other,  the  resistance 
of  the  circuit  is  equal  to  the  sum  of  the  resistances  of 
its  several  parts.  In  calculating  the  resistance  of 
such  a  circuit,  the  resistance  of  each  part  should  first 
be  calculated,  and  the  sum  of  these  resistances  will 
be  the  total  resistance  of  the  circuit. 

Resistance  Affected  by  Heating.  The  resistance 
of  metals  depends  upon  the  temperature,  and  the 
resistance  is  increased  by  heating.  The  heating  of 
some  substances,  among  which  is  carbon,  causes  a 
decrease  in  their  resistance.  The  resistance  of  the 
filament  of  an  incandescent  lamp  when  lighted  is  only 
about  half  as  great  as  when  cold.  All  metals,  how- 
ever, have  their  resistance  increased  by  a  rise  in  tern- 


MOTION     PICTURE     PROJECTION 


perature.  The  percentage  increase  in  resistance  with 
rise  of  temperature  varies  with  the  different  metals, 
and  varies  slightly  for  the  same  metal  at  different 
temperatures.  The  increase  is  practically  uniform 
for  most  metals  throughout  a  considerable  range  of 
temperature.  The  resistance  of  copper  increases 
about  A  per  cent,  per  degree  Centigrade.  The  per- 
centage increase  in  resistance  for  alloys  is  much  less 
than  for  the  simple  metals.  Standard  resistance 
coils  are  therefore  made  of  alloys,  as  it  is  desirable 
that  their  resistance  should  be  as  nearly  constant  as 
possible. 

QUANTITY,  ENERGY  AND  POWER. 

Quantity.  The  strength  of  a  current  is  deter- 
mined by  the  amount  of  electricity  which  passes 
any  cross-section  of  the  conductor  in  a  second; 
that  is,  current  strength  expresses  the  rate  at  which 
electricity  is  conducted.  The  quantity  of  electric- 
ity conveyed  evidently  depends  upon  the  current 
strength  and  the  time  the  current  continues. 

The  Coulomb.  The  coulomb  is  the  unit  of  quan- 
tity and  is  equal  to  the  amount  of  electricity  which 
passes  any  cross-section  of  the  conductor  in  one 
second  when  the  current  strength  is  one  ampere.  If 
a  current  of  one  ampere  flows  for  two  seconds,  the 
quantity  of  electricity  delivered  is  two  coulombs,  and 
if  two  amperes  flow  for  one  second  the  quantity  is 
also  two  coulombs.  With  a  current  of  four  amperes 
flowing  for  three  seconds,  the  quantity  delivered  is  12 
coulombs.  The  quantity  of  electricity  in  coulombs  is 
therefore  equal  to  the  current  strength  in  amperes 
multiplied  by  the  time  in  seconds. 


MOTION     PICTURE     PROJECTION  29 

Energy.  Whenever  a  current  flows,  a  certain 
amount  of  energy  is  expended,  and  this  may  be 
transformed  into  heat,  or  mechanical  work,  or  may 
produce  chemical  changes.  The  unit  of  mechanical 
energy  is  the  amount  of  work  performed  in  raising  a 
mass  of  one  pound  through  a  distance  of  one  foot, 
and  is  called  the  foot-pound.  The  work  done  in 
raising  any  mass  through  any  height  is  found  by 
multiplying  the  number  of  pounds  in  that  mass  by 
the  number  of  feet  through  which  it  is  lifted.  Elec- 
trical work  may  be  determined  in  a  corresponding 
manner  by  the  amount  of  electricity  transferred 
through  a  difference  of  potential. 

The  Joule.  The  joule  is  the  unit  of  electrical 
energy,  and  is  the  work  performed  in  transferring  one 
coulomb  through  a  difference  of  potential  of  one  volt. 
That  is,  the  unit  of  electrical  energy  is  equal  to  the 
work  performed  in  transferring  a  unit  quantity  of 
electricity  through  a  unit  difference  of  potential.  It 
is  evident  that  if  2  coulombs  pass  in  a  circuit  and  the 
difference  of  potential  is  one  volt,  the  energy  ex- 
pended is  2  joules.  Likewise,  if  1  coulomb  passes  and 
the  potential  difference  is  2  volts,  then  the  energy 
expended  is  also  2  joules.  Therefore,  to  find  the 
number  of  joules  expended  in  a  circuit,  multiply  the 
quantity  of  electricity  by  the  potential  difference 
through  which  it  is  transferred. 

Power.  Power  is  the  rate  of  doing  work,  and 
expresses  the  amount  of  work  done  in  a  certain  time. 
The  horse-power  is  the  unit  of  mechanical  energy, 
and  is  equal  to  33,000  foot-pounds  per  minute,  or 
550  foot-pounds  per  second.  A  certain  amount  of 
work  may  be  done  in  one  hour  or  two  hours,  and  in 


30  MOTION     PICTURE     PROJECTION 

stating  the  work  done  to  be  so  many  foot-pounds 
or  so  many  joules,  the  rate  at  which  the  work  is 
done  is  not  expressed.  Power,  on  the  other  hand, 
includes  the  rate  of  working. 

It  is  evident  that  if  it  is  known  that  a  certain 
amount  of  work  is  done  in  a  certain  time,  the  rate 
at  which  the  work  is  done,  or  the  power,  may  be 
obtained  by  dividing  the  work  by  the  time,  giving 
the  work  done  per  unit  of  time. 

The  Watt.  The  electrical  unit  of  power  is  the 
watt,  and  is  equal  to  one  joule  per  second;  that  is, 
when  one  joule  of  work  is  expended  in  one  second, 
the  power  is  one  watt.  If  the  number  of  joules  ex- 
pended in  a  certain  time  is  known,  then  the  power  in 
watts  is  obtained  by  dividing  the  number  of  joules 
by  the  time  in  seconds. 

The  power  is  obtained  by  multiplying  the  current 
by  the  voltage,  or  by  multiplying  the  square  of  the 
current  by  the  resistance. 

The  watt  is  sometimes  called  the  volt-ampere. 

For  large  units  the  kilowatt  is  used,  and  this  is 
equal  to  1,000  watts.  The  common  abbreviation  for 
kilowatt  is  K.  W.  The  kilowatt-hour  is  a  unit  of 
energy,  and  is  the  energy  expended  in  one  hour  when 
the  power  is  one  kilowatt. 

Equivalent  of  Electrical  Energy  in  Mechanical 
Units.  The  common  unit  of  mechanical  energy  is 
the  foot-pound,  and  from  experiment  it  has  been 
found  that  one  joule  is  equivalent  to  .7373  foot- 
pound; that  is,  the  same  amount  of  heat  will  be 
developed  by  one  joule  as  by  .7373  foot-pound  of 
work. 

As  one  horse-power  is  equal  to  550  foot-pounds 


MOTION     PICTURE     PROJECTION  31 

per  second,  it  follows  that  this  rate  of  working  is 
equivalent  to 
550 

=  746  joules  per  second  (approx.). 

.7373 

Hence  one  horse-power  is  equivalent  to  746  watts. 
Therefore,  to  find  the  equivalent  of  mechanical 
power  in  electrical  power,  multiply  the  horse-power 
by  746;  and  to  find  the  equivalent  of  electrical 
power  in  mechanical  power,  divide  the  number  of 
watts  by  746. 

Ohms  Law.  Ohms  law  is  merely  the  fundamental 
principle  on  which  most  of  electrical  mathematics 
are  worked. 

A  series  of  formulas  used  by  electricians  in  figur- 
ing voltage,  amperage  and  resistance : 

FORMULA  1 

To  find  the  amount  of  current  flowing  in  a  circuit  divide  the 
voltage  by  the  resistance,  or 

Electric  Motive  Force 

Current  = 

Resistance 

For  instance,  if  we  have  a  line  voltage  of  100  and  our  circuit 
has  a  resistance  of  5  ohms,  then  by  dividing  100  by  5,  we 
would  get  our  amperage. 

5  )   100  (  20 
100 

so  we  would  have  20  amperes. 

FORMULA  2 

To  find  the  amount  of  resistance  in  a  circuit,  divide  the  voltage 
by  the  amount  of  amperage  drawn,  or 


MOTION    PICTURE    PROJECTION 

Electric  Motive  Force 
Resistance  = 


Current 

For  Instance,  suppose  we  have  a  line  voltage  of  100  and  are 
using  20  amperes  at  arc  lamp,  then  by  dividing  the  100 
by  20  we  would  get  the  amount  of  resistance  we  have  In 
our  circuit 

20  )  100  (5 
100 

to   we   would   have   5   ohms    resistance    in   our    circuit 

FOEMULA  8 

To  find  the  voltage  of  a  circuit,  multiply  the  amount  of  am- 
peres drawn  by  the  amount  of  resistance,  or 

Electric  Motive  Force  =  Amperes  Times  Resistance 

For  example:  If  we  had  20  amperes  at  arc  and  our  circuit  was 
offering  5  ohms  resistance,  then  by  multiplying  20  by  6  we 
would  get  our  voltage. 

20  amperes 
0  ohms 


100  volts 

To  find  Volt*.    Multiply  number  of  Amperes  by  amount  of 

Resistance. 

To  find  Rffiftance.     Divide  Voltage  by  Amperage. 
To  find  Amperage.    Divide  Voltage  by  Resistance. 

To  find  Watt*.    Multiply  Voltage  by  Amperage. 

To  find  Amp*.    Divide  Watts  by  Volts. 

To  find  Volt*.    Divide  Watts  by  Amperage. 


PICTURE     PROJECTION 


GENERATION  OF  ELECTRICITY 

Everyone  is  acquainted  with  the  horseshoe  mag- 
ajMJ   the  small  pocket  compass,  and   these  two 
articles  will  serve  as  an  illustration. 

-»•  if  one  of  the  legs  of  the  horseshoe  magnet  be 
brought  mar  tl  pu.s*,  it  will  be  found  thai  one 

?h.-  needle  will  be  attracted  to  it,  whilst  if  Uie 
other  leg  be  present. •<!  the  other  « -mi  of  tl,.-  intdlc  is 
attracted.  One  leg,  at  its  end,  has  north  polarity, 
because  it  attracts  the  south  pole  of  the  compass 
needle,  whilst  the  other  end,  having  south  polar 
attracts  the  north  end  of  the  needle,  so  that  between 
the  ends  of  the  two  legs  there  exists  what  is  known  as 
a  "magnetic  field,"  or  space  wherein  magnetic  lines 
of  force  are  present.  These  lines  of  force  are  invis- 
ible, but  if  the  magnet  be  laid  on  a  table,  and  a  piece 
of  paper  put  over  it,  and  if  on  the  paper  be  sprinkled 
some  iron  filings  it  will  be  found,  when  the  paper  is 
tapped  by  the  finger,  that  these  filings  group  them- 
selves around  the  ends  of  tin-  magm  tin  circles,  being 
closer  together  at  tin-  ends  than  further  away,  or 
higher  up  towards  the  Urn!  of  the  horseshoe.  The 
magnetic  field  is  the  most  «!•  UN.  Ixtw.-m  the  legs  of 
the  magnet  at  their  ends.  If  a  copper  wire  be  passed 
up  and  down  between  the  ends  of  the  legs  an  electric 
current  will  be  induced  in  the  wire,  its  direction  of 
flow  varying  with  the  upward  and  downward  mot 
of  the  wire.  In  this  case  the  electricity  is  obtained 
from  the  magnet  by  "induction."  this  being  the  ele- 

•.tary  principle  upon  which  all  dynamos,  whether 
for  lighting  or  power,  is  based.     In  the  dynamo  the 


34  MOTION     PICTURE     PROJECTION 

horseshoe  is  replaced  by  electro-magnets,  the  large 
stationary  pieces  of  soft  iron  surrounded  with  cov- 
ered copper  wire,  whilst  the  armature,  the  part 
which  revolves,  replaces  the  thin  pieces  of  copper 
wire  in  the  above  simple  experiment.  The  armature 
does  not  touch  the  magnets,  and  there  is  no  friction 
except  that  in  the  bearings  of  the  armature  shaft, 
in  which  it  is  necessary  to  revolve,  and  which  is  made 
as  easy  as  possible  by  a  liberal  supply  of  oil.  It  will 
also  be  seen  that  the  electricity  is  not  pumped  from 
the  atmosphere,  but  is  simply  the  revolution  of  a 
bundle  of  copper  wires  between  the  poles  of  a  pow- 
erful electro-magnet.  The  ends  of  the  electro-mag- 
nets are  thickened  out,  and  each  one  made  semi-cir- 
cular so  that  the  armature  may  revolve  between  the 
north  and  south  poles  and  the  electro-magnets,  con- 
sisting of  soft  iron,  are  wound  round  with  insulated 
copper  wire,  so  that  a  portion  of  the  electricity  gen- 
erated in  the  armature  may  be  shunted  around  them 
and  so  keep  always,  whilst  the  dynamo  is  in  action, 
as  powerful  electro-magnets.  When  the  dynamo  is 
stopped,  these  magnets  retain  a  small  amount  of 
magnetism,  which  is  gradually  strengthened  to  its 
maximum  as  the  armature  is  started  revolving,  the 
dynamo  "building  up"  as  it  is  termed.  Anyone  who 
has  watched  the  starting  up  of  a  dynamo  will  have 
noticed  that  when  running  slowly  the  lamp  connected 
to  it  as  "pilot"  gradually  shows  a  red  filament,  which 
becomes  brighter  as  the  revolutions  increase,  until, 
when  the  correct  speed  is  reached  for  which  the 
dynamo  was  designed,  the  right  voltage  will  show 
on  the  voltmeter  and  the  pilot  lamp  attain  its  full 
brilliancy. 


MOTION     PICTURE     PROJECTION  35 

The  armature  of  the  dynamo  is  the  only  part 
which  revolves,  and  this  consists  of  a  steel  shaft  sup- 
ported in  bearings  at  each  end,  to  which  the  pulley 
is  attached  to  receive  the  belt  for  transmitting  the 
power  from  the  engine  to  the  dynamo.  On  the  shaft 
are  built  up  thin  sheets  of  soft  iron  provided  with 
grooves  in  which  the  different  sections  of  insulated 
copper  wire  are  laid  lengthwise,  their  ends  being 
connected  to  what  is  called  the  "commutator"  fas- 
tened to  the  shaft.  This  consists  of  bars  of  copper 
made  into  a  drum,  each  bar  being  insulated  from  its 
neighbour  by  means  of  strips  of  mica,  and  on  the 
commutator  rest  lightly  the  carbon  or  copper 
brushes  to  convey  the  electricity  to  the  lamps  or 
motors. 

The  number  of  coils  of  wire  on  the  armature 
depends  upon  the  voltage  the  dynamo  is  designed  to 
give,  and  the  speed  at  which  it  has  to  run,  also  upon 
the  strength  of  the  magnetic  field  of  the  electro- 
magnets ;  and  the  thickness  of  these  conductors  will 
depend  upon  whether  it  has  to  give  a  large  or  small 
current  strength.  If  the  voltage  is  to  be  high,  and 
small  current  strength,  many  conductors  of  fine  wire 
are  employed;  if  the  voltage  required  is  to  be  low, 
and  large  current  strength,  a  few  sections  of  thick 
wire  are  required. 

A  machine  as  above  described  is  known  as  a  con- 
tinuous-current dynamo,  to  distinguish  it  from  an 
"alternator,"  and  the  current  obtained  from  it  flows 
in  a  continuous  circuit  from  the  positive  brush  or 
collector  on  the  commutator,  through  the  lamps  or 
motors,  and  completes  the  circuit  to  the  other  brush. 

The  mistaken  notion  of  electricity  being  obtained 


MOTION     PICTURE     PROJECTION 


by  friction  has  probably  arisen  from  the  fact  that, 
resting  on  the  top  and  bottom  of  the  commutator 
are  carbon  or  copper  brushes,  but  these  are  for  the 
purpose  of  turning  the  currents,  which  are  gener- 
ated in  the  armature  as  alternating  currents,  into 
one  direction.  They  also  act  as  collectors  to  convey 
the  electricity  to  the  external  circuit  for  lamps, 
motors,  or  other  electricity-consuming  devices,  and 
do  not  offer  practically  any  friction,  only  resting 
lightly  against  the  surface  of  the  revolving  commu- 
tator. 

For  supplying  extensive  areas  such  as  towns 
where  the  demand  for  electricity  is  scattered,  alter- 
nating-current machines  or  "alternators"  are  em- 
ployed which  do  not  require  commutators,  the  high 
voltage  generated,  2,000  volts  and  upwards,  being 
led  to  transformer  stations,  where  it  is  reduced,  by 
means  of  stationary  transformers,  to  110  and  220 
volts  for  feeding  lamps  direct,  or  for  motors  and 
other  uses.  The  field  magnets  of  these  alternators 
are  energised  by  a  continuous  or  direct  current  sup- 
plied from  a  small  dynamo  generally  fixed  on  the 
alternator  shaft,  and  running  at  the  same  speed. 


MOTION     PICTURE     PROJECTION  37 


ALTERNATING  CURRENTS 

A  continuous  or  direct  current  is  one  of  uniform 
strength  always  flowing  in  one  direction,  while  an 
alternating  current  is  continually  changing  both  its 
strength  and  direction.  The  various  principles  and 
facts  concerning  direct  current  distribution  apply 
also  to  alternating  current  systems.  But  in  addi- 
tion to  the  simple  phenomena  due  to  the  resistance, 
which  occur  with  direct  currents,  there  are  certain 
additional  factors  that  must  be  considered  in  con- 
nection with  alternating  current  transmission. 

The  flow  of  a  direct  current  is  entirely  determined 
by  the  ohmic  resistance  of  the  various  parts  of  the 
circuit.  The  flow  of  an  alternating  current  depends 
upon  not  only  the  resistance,  but  also  upon  any 
inductance  (self  or  mutual)  or  capacity  that  may  be 
contained  in  or  connected  with  the  circuit.  These 
two  factors,  inductance  and  capacity,  have  no  effect 
upon  a  direct  current  after  a  steady  flow  has  been 
established,  which  usually  requires  only  a  fraction  of 
a  second.  In  an  alternating  current  circuit  either 
or  both  of  them  may  be  far  more  important  than 
the  resistance  and  in  some  cases  may  entirely  con- 
trol the  action  of  the  current.  Alternating  cur- 
rent problems  involving  the  consideration  of  three 
factors  are  usually  more  complicated  and  difficult 
to  solve  than  those  relating  to  direct  currents.  By 
an  extension  of  the  principles  and  methods  employed 
for  direct  currents,  however,  alternating  current 
systems  can  be  designed  correctly  and  without  great 
difficulty. 


38  MOTION     PICTURE     PROJECTION 

The  only  reason  practically  for  employing  alter- 
nating currents  for  electric  lighting  and  power  pur- 
poses is  the  economy  effected  in  the  cost  of  trans- 
mission, which  is  accomplished  by  the  use  of  high 
voltages  and  transformers.  The  cross  section  of  a 
wire  to  convey  a  given  amount  of  electrical  energy 
in  watts  with  a  certain  "drop"  or  loss  of  potential 
in  volts,  is  inversely  proportional  to  the  square  of 
the  voltage  supplied;  that  is,  it  requires  a  wire  of 
only  one-quarter  the  cross-section  and  weight  if  the 
initial  voltage  is  doubled.  The  great  advantage  thus 
obtained  by  the  use  of  high  voltages  can  be  realized 
either  by  a  saving  in  the  weight  of  wire  required  or 
by  transmitting  the  energy  to  a  greater  distance 
with  the  same  weight  of  copper. 

When  the  alternating  current,  or  E.  M.  F.,  has 
passed  from  zero,  to  its  maximum  value,  to  zero,  in 
one  direction,  then  from  zero,  to  its  maximum  value, 
to  zero,  in  the  other  direction,  the  complete  set  of 
values  passed  through  repeatedly  during  that  time  is 
called  a  cycle.  This  cycle  of  changes  constitutes  a 
complete  period,  and  since  it  is  repeated  indefinitely 
at  each  revolution  of  the  armature  the  currents  pro- 
duced by  such  an  E.  M.  F.  are  called  periodic  cur- 
rents. The  number  of  complete  periods  in  one  sec- 
ond is  called  the  frequency  of  the  pressure  or  cur- 
rent. 

The  term  frequency  is  applied  to  ijie  number  of 
cycles  completed  in  a  unit  of  time — one  second.  The 
word  alternations  is  sometimes  used  to  express  the 
frequency  of  an  alternator,  meaning  the  number  of 
alternations  per  minute.  In  practice  the  frequency 
is  usually  expressed  in  cycles.  An  alternation  is  half 


MOTION     PICTURE     PROJECTION 


a  period  or  cycle;  since  the  current  changes  its  direc- 
tion at  each  half  cycle,  it  follows  that  the  number  of 
alternations  or  reversals  is  twice  the  number  of 
cycles. 

If  the  current  from  an  alternator  performed  the 
cycle  sixty  times  a  second,  it  would  be  said  to  have  a 
•frequency  of  60  cycles,  which  would  mean  120  alter- 
nations per  second,  or  120  X  60  seconds  =  7200  al- 
ternations per  minute. 

The  frequency  of  an  alternating  current  is  always 
that  of  the  E.  M.  F.  producing  it. 

Unless  otherwise  specified,  frequencies  are  in  the 
term  of  cycles,  thus:  a  frequency  of  60  means  60 
cycles.  The  frequency  of  commercial  alternating 
current  depends  upon  the  work  it  is  expected  to  do. 
For  power  a  low  frequency  is  desirable,  frequencies 
for  this  purpose  varying  from  60  down  to  25. 

For  lighting  work  frequencies  from  60  to  125  are 
in  general  use.  Very  low  frequencies  cannot  be  used 
for  lighting  owing  to  the  flickering  of  the  lamps. 
A  number  of  central  stations  have  adopted  a  fre- 
quency of  60  as  a  standard  for  lighting  and  power 
transmission. 

Most  of  the  peculiarities  that  alternating  current 
exhibits,  as  compared  with  direct  current,  are  due 
more  or  less  to  the  fact  that  an  alternating  current 
is  constantly  changing,  whereas  a  continuous  current 
flows  uniformly  in  one  direction.  When  a  current  flows 
through  a  wire  it  sets  up  a  magnetic  field  around 
the  wire,  and  since  the  current  changes  continually 
this  magnetic  field  will  also  change.  Whenever  the 
magnetic  field  surrounding  a  wire  is  made  to  change, 
an  E.  M.  F.  is  set  up  in  the  wire,  and  this  induced 


40  MOTION     PICTURE     PROJECTION 

E.  M.  F.  opposes  the  current.  For  example,  when 
the  current  rises  in  the  positive  direction,  the  mag- 
netism increases,  in  let  us  say,  the  clockwise  direc- 
tion about  the  conductor;  after  the  current  passes 
the  maximum  value  and  begins  to  decrease,  the  lines 
of  force  commence  to  collapse,  reaching  zero  value 
when  the  current  reaches  zero ;  then  when  the  current 
rises  in  the  negative  direction  the  magnetic  lines 
expand  in  the  counter-clockwise  direction,  and  so  on. 
The  result  is  that  the  counter  E.  M.  F.  of  self-induc- 
tion, instead  of  being  momentary,  as  when  the  cur- 
rent is  made  and  broken  through  a  conductor,  is 
continuous,  but  varies  in  value  like  the  applied  E. 
M.  F.  and  the  current.  The  value  of  an  induced 
E.  M.  F.  is  proportional  to  the  rapidity  with  which 
lines  of  force  are  cut  by  the  conductor,  and  as  the 
lines  of  force  vary  most  rapidly  when  passing  the 
zero  point  (changing  from  +  to  — )  or  vice  versa, 
the  induced  E.  M.  F.  is  maximum  at  that  moment. 

When  the  current,  and  therefore  the  magnetism,  is 
at  the  maximum  value  in  either  direction,  its  strength 
varies  very  little  within  a  given  momentary  period  of 
time,  and  consequently  the  induced  E.  M.  F.  is  zero 
at  the  moment  the  current  and  magnetism  is  at  maxi- 
mum, the  E.  M.  F.  of  self-induction  not  rising  and 
falling  in  unison  with  the  applied  E.  M.  F.  and  the 
current,  but  lagging  behind  the  current  exactly  a 
quarter  of  a  cycle. 

This  property  of  a  wire  or  coil  to  act  upon  itself 
inductively  (self-induction)  or  of  one  circuit  to  act 
inductively  on  another  independent  circuit  (mutual 
induction)  is  termed  Inductance. 


MOTION     PICTURE     PROJECTION  41 

The  Unit  or  Coefficient  of  inductance  is  called  the 
henry,  the  symbol  for  which  is  L. 

Many  devices  met  with  in  alternating  current  work 
have  this  property  of  inductance.  A  long  transmis- 
sion line  has  a  certain  amount  of  it,  as  have  induction 
motors  and  transformers. 

The  effect  of  inductance  in  an  alternating  current 
circuit  is  to  oppose  the  flow  of  current  on  account  of 
the  counter  E.  M.  F.  which  is  set  up.  This  opposi- 
tion may  be  considered  as  an  apparent  additional 
resistance  and  is  called  reactance  to  distinguish  it 
from  ohmic  resistance. 

Reactance  is  expressed  in  ohms,  like  resistance,  be- 
cause it  constitutes  an  opposition  to  the  flow  of  the 
current.  Unlike  resistance,  however,  this  opposition 
does  not  entail  any  loss  of  energy  because  it  is  due 
to  a  counter  pressure  and  is  not  a  property  analo- 
gous to  friction.  Its  effect  in  practice  is  to  make  it 
necessary  to  apply  a  higher  E.  M.  F.  to  a  circuit  in 
order  to  pass  a  given  current  through  it  than  would 
be  required  if  only  the  resistance  of  the  circuit  op- 
posed the  current. 

ELECTRICAL  RESISTANCE 

THE  RHEOSTAT 

The  question  of  electrical  resistance  as  applied  to 
the  projection  circuit  has  long  been  a  stumbling 
block  to  a  great  number  of  operators,  while  we  ad- 
mit that  the  subject  is  complicated,  and  some  of  its 
phrases  hard  to  follow,  it  is  essential  that  the  theory 
of  electrical  resistance  be  mastered  if  we  are  desirous 
of  progressing  in  the  art  of  projection. 


42 


MOTION    PICTURE     PROJECTION 


Electrical  resistance  is  that  property  of  anything 
in  an  electric  circuit  which  will  resist  the  flow  of  cur- 
rent. The  effect  of  resistance  is  to  produce  heat. 

The  unit  of  electrical  resistance  is  the  ohm,  and  is 
so  named  after  Dr.  G.  S.  Ohm  who  gave  us  the  series 
of  formulas  now  known  as  Ohm's  Law;  it  will  be 
necessary  to  thoroughly  understand  the  working  of 
this  law  to  be  able  to  work  out  any  of  the  numerous 
problems  in  electrical  resistance.  Ohm's  Law  states 
that:  The  current  is  directly  proportional  to  the 
voltage  and  inversely  proportional  to  the  resistance. 
This  means  that  if  the  voltage  of  a  circuit  be  in- 
creased the  current  will  proportionally  increase,  and 
should  the  resistance  of  a  circuit  be  increased  then 
the  current  will  be  proportionately  decreased.  Should 
the  voltage  be  decreased  there  will  be  a  proportional 
decrease  in  the  current,  if  the  resistance  in  the  cir- 


FIG .  1. 


MOTION     PICTURE     PROJECTION 


48 


cuit  is  decreased  there  will  be  a  proportional  increase 
in  current.     Expressed  mathematically 

Electric  Motive  Force 

Current  — 

Resistance 

Current  is  equal  to  the  Electric  Motive  Force  (Volt- 
age) divided  by  the  Resistance  (in  ohms)  or 

E 
r* 

~R 

If  by  dividing  the  voltage  by  the  resistance  we  get 
the  amount  of  current,  then  by  dividing  the  voltage 


H 


44  MOTION     PICTURE     PROJECTION 

by  the  current  we  will  naturally  get  the  amount  of 
resistance  in  our  circuit,  or  — 

EMF 


C 

and  so  to  find  the  voltage  all  we  have  to  do  is  to 
multiply  the  current  by  the  amount  of  resistance  in 
our  circuit,  or  — 


It  will  thus  be  seen  that  providing  we  have  two 
known  quantities  the  third  unknown  quantity  can 
easily  be  obtained  by  the  use  of  one  of  the  above 
formulas;  for  instance,  let  us  suppose  that  we  have 
a  line  voltage  of  100  and  our  circuit  has  a  total 
resistance  of  5  ohms,  then  by  dividing  the  100  (volts) 
by  5  (ohms)  we  find  our  current  to  be  20  (amperes). 

Providing  we  knew  there  was  a  line  voltage  of 
100  and  we  were  drawing  20  amps  at  our  arc,  then 
by  dividing  the  100  (volts)  by  20  (amperes)  we 
would  get  the  amount  of  resistance  in  our  circuit 
which  would  be  5  (ohms). 

By  the  foregoing  it  is  evident  that  the  amount  of 
current  we  will  get  at  the  arc,  depends  on  the  EMF 
and  the  amount  of  resistance  in  our  circuit. 

Resistance  is  the  inverse  to  conductivity. 

Current  encounters  resistance  when  passed  over 
any  conductor.  Copper,  silver  and  aluminum  are 
good  conductors,  so  offer  very  little  resistance,  while 
metals  like  iron  and  German  silver  are  poor  con- 
ductors and  offer  a  much  higher  resistance  to  the 
flow  of  current. 

The  resistance  of  any  conductor  increases,  as  the 
length  of  the  conductor  is  increased,  as  the  diameter 


MOTION    PICTURE     PROJECTION 


45 


of  the  conductor  is  decreased ;  or  as  the  temperature 
of  conductor  is  increased  (the  resistance  of  insu- 
lating material  and  carbon  decreases  with  an  increase 
of  temperature).  To  find  the  resistance  of  a  copper 
wire,  multiply  its  length  in  feet  by  10.5  and  divide 
the  product  by  its  area  in  circular  mills. 

Resistance  is  introduced  into  our  projection  cir- 
cuit for  two  reasons,  first  to  bring  the  supply  volt- 
age down  to  a  suitable  voltage  for  maintaining  an 
arc  and  secondly  to  act  as  ballast  on  our  line. 

The  voltage  supply  generally  runs  around  220  or 
110  volts  and  as  we  only  need  approximately  50 
volts  to  maintain  a  D.C.  arc  (for  A.C.  the  voltage 


Power's  Rheostat  with 
cover    removed    show- 
ing    arrangement     of 
coils. 


should  be  35-40  volts)  it  is  apparent  that  we  must 
introduce .  some  medium  to  act  as  a  resistance  to 
secure  the  desired  voltage  across  the  arc.  This  is 
generally  accomplished  by  connecting  a  rheostat  or 
a  number  of  rheostats  on  our  line  in  series  with  the 
arc.  The  majority  of  operators  are  thoroughly 
familiar  with  the  construction  of  the  various  makes 


46 


MOTION     PICTURE     PROJECTION 


of  rheostats  now  on  the  market,  but  for  the  benefit 
of  those  who  are  not,  let  us  here  explain  their  gen- 
eral construction  and  operation. 

A  rheostat  is  constructed  of  a  number  of  metal 
coils  or  grids  (these  coils  or  grids  are  made  of  some 
metal  offering  high  resistance  to  the  flow  of  current 
over  them,  generally  iron  or  German  silver)  con- 
nected in  series,  these  coils  or  grids  are  mounted  on 
a  metal  frame  from  which  they  are  insulated,  the 
whole  thing  being  covered  with  a  perforated  metal 
cover.  The  first  and  last  coil  are  each  connected  to 
a  terminal  which  allows  for  the  connection  of  the 
conductors  ( see  Fig.  1).  The  current  enters  the 
rheostat  through  terminal  P,  then  passes  through 
the  coil  or  grid  A  to  B,  then  to  C  and  so  on  till  it 
has  passed  through  each  of  the  coils  in  turn  and 
leaves  the  rheostat  through  terminal  S.  Most  of 
the  rheostats  manufactured  today  are  of  the  adjust- 
able type,  so  constructed  that  by  the  turning  of  an 
adj  usable  lever  a  number  of  the  coils  can  be  cut  in 
or  out  of  the  circuit,  thus  cutting  in  or  out  resist- 
ance, thereby  lowering  or  increasing  the  amperage 
at  the  arc.  Fig.  2  is  an  elementary  drawing  showing 
how  this  is  accomplished.  P  is  the  terminal  through 
which  the  current  enters  the  rheostat,  S  the  terminal 


RHEOSTATS   IN    SERIES 
Fig.  8 


MOTION    PICTURE     PROJECTION  47 

through  which  it  leaves  after  having  passed  through 
the  series  of  coils  or  grids.  As  will  be  seen  by  re- 
ferring to  the  diagram  (Fig.  2)  it  depends  on  which 
contact  points  1,  2,  3,  4  or  5,  the  adjusting  lever  N 
is  placed  as  to  the  number  of  coils  through  which  the 
current  will  pass.  With  the  lever  "N"  or  contact 
No.  1  the  current  will  pass  through  coils  A  B  C  D 
only,  by  turning  the  lever  to  contact  4,  two  coils  K 
and  L  will  be  cut  out  of  the  circuit;  while  if  lever  is 
placed  on  contact  5  the  current  must  pass  through 
all  of  the  coils  or  grids  before  leaving  through  ter- 
minal S. 

Rheostats  are  always  marked  for  the  voltage  they 
are  to  be  used  on  and  the  amount  of  current  they 
will  give  at  the  arc.  A  rheostat  marked  110  volts, 
40  to  65  amperes  simply  means  that  providing  it  is 
connected  on  a  110  volt  line  it  will  give  40  amperes 
at  the  arc  with  the  lever  on  low  contact  point,  65 
amperes  if  the  lever  is  placed  on  high.  Two  or  more 
rheostats  can  be  connected  together  in  series  or  mul- 
tiple, but  remember  that  rheostats  must  always  be 
connected  in  series  with  the  arc. 

Figure  3  shows  the  rheostats  connected  in  series 
with  each  other  and  in  series  with  the  arc.  Fig.  4 
shows  the  rheostat  connected  in  multiple  with  each 
other  and  in  series  with  the  arc. 

Never  under  any  circumstances  connect  110  volt 
rheostat  either  singly  or  in  multiple  on  a  220  volt 
line,  as  the  coils  will  be  heated  above  their  rated  ca- 
pacity and  probably  will  burn  out.  However  two 
110-volt  rheostats  if  connected  in  series  with  each 
other  can  be  used  on  a  220-volt  line  until  such  time 
as  a  220-volt  rheostat  can  be  obtained. 


48 


MOTION     PICTURE     PROJECTION 


MOTION    PICTURE     PROJECTION 


49 


Where  a  number  of  rheostats  are  connected  to- 
gether in  series  the  resistance  in  our  circuit  is  equal 
to  the  sum  of  the  separate  rheostats.  So  by  taking 
three  rheostats  that  have  a  resistance  of  4,  6  and  10 
ohms,  respectively,  and  connecting  same  in  series  with 
each  other  and  in  series  with  the  arc,  we  would  have  a 
total  of  4+6+10=20  ohms  resistance  from  the 
three.  Where  a  number  of  rheostats  are  connected 
together  in  multiple,  the  resistance  in  our  circuit  is 
equal  to  their  product  divided  by  their  sum,  or  — 


24° 

-  =  -  =  12  ohms. 
4-f-6-flO          20 

Rheostats  are  extremely  wasteful,  being  about  50 
per  cent  efficient  when  new;  the  electrical  energy  is 
converted  into  heat  which  goes  to  waste.  For  in- 
stance, let  us  suppose  that  the  supply  voltage  is  110 
and  that  we  are  drawing  50  amperes  at  the  arc, 
110X50=5,500  watts  registered  on  the  meter  and 
to  be  paid  for.  Our  arc  voltage  is  approximately 
50  volts,  so  50X50=2,500  watts,  the  amount  actu- 
ally used  at  the  arc,  5,500  —  2,500=3,000  watts 
wasted  in  the  rheostat.  As  the  line  voltage  is  in- 


RHEOSTAT 
f             1° 

r 

RHEOSTATS  IN   MULTIPLE 


Fig.  4 


50  MOTION     PICTURE     PROJECTION 

creased  the    percentage  wasted    is    proportionately 
much  greater. 

Rheostats  should  be  installed  outside  the  projec- 
tion room  wherever  possible,  preferably  on  a  shelf 
near  the  ceiling  and  located  near  enough  to  the  vent 
to  allow  the  heat  from  the  rheostat  to  be  carried  to 
the  open  air.  They  should  be  kept  away  from  any- 
thing inflammable.  Where  the  rheostat  is  located 
away  from  the  projector  it  is  advisable  to  have  a 
control  switch  so  placed  that  the  operator  can  cut 


Separate  Unit  of  Robin  Multiple 
Unit   Rheostat 

in  or  out  resistance  without  having  to  leave  his  ma- 
chine. All  electric  connections  should  be  kept  tight 
to  prevent  arcing;  remember  copper  oxodizes  under 
excessive  heat  and  additional  resistance  is  thus  added 
to  the  circuit. 

MULTIPLE  UNIT  RHEOSTATS 

A  multiple  rheostat  consists  of  several  indepen- 
dent rheostats  arranged  in  a  housing;  each  unit  is 
a  separate  arc  rheostat,  delivering  two  and  one- 


MOTION     PICTURE     PROJECTION  51 

half  amperes  at  an  arc  voltage  of  58.  In  the  event 
of  any  unit  burning  out  the  balance  are  still  oper- 
able. Each  rheostat  consists  of  from  10  to  40  units, 
depending  on  the  capacity.  Rheostats  used  on  big 
installations  are  arranged  for  remote  control,  the 
control  panel  board  with  radial  multiple  switch  is 
placed  in  the  front  wall  of  booth  under  the  look-out 
port  holes. 


Robin  Multiple  Unit  Rheostat  With  Manual 
Remote   Control  Wheel 


52 


MOTION     PICTURE    PROJECTION 


O 


o 


o 


o 


o 


Mil  I 


o 


o 


o 


MOTION     PICTURE     PROJECTION 


53 


NEW  DEVICE  FOR  CONTROLLING 
RESISTANCE 

A  patent  has  just  been  granted  for  an  electrical 
regulating  switch  for  limiting  the  current  in  two 
separate  circuits  to  a  predetermined  maximum.  The 
invention  relates  to  a  new  or  improved  regulating 
switch  and  is  particularly  adapted  for  use  in  con- 
nection with  motion-picture  projectors,  especially 
in  cases  where  two  or  more  machines  are  used.  The 


<5 


object  of  the  invention  consists  in  a  new  or  improved 
arrangement  whereby  the  amount  of  current 
switched  on  in  either  one  or  two  arcs,  is  limited  to  a 
predetermined  maximum. 

According  to  the  inventor  the  switch  arms  for 
each  set  of  resistances  are  arranged  to  move  over 
the  usual  radially  arranged  contact  studs,  prefer- 
ably disposed  side  by  side  or  one  above  the  other. 


54 


MOTION     PICTURE     PROJECTION 


These  switch  arms  are  connected  by  two  hinged  or 
pivoted  connecting  members,  the  inner  ends  of  each 
of  which  are  pivoted  to  one  another,  while  their  op- 
posite ends  are  connected  to  the  respective  switch 
arms.  The  inner  ends  of  each  of  the  connecting 
members  are  provided  with  projecting  stops,  each 
arranged  to  engage  the  opposite  member  and  thus 
limit  the  stroke  or  extent  of  rotation  of  either  switch 
arm  relatively  to  the  other. 

In  order  that  the  invention  may  be  readily  under- 
stood, reference  is  directed  to  the  accompanying 
drawings,  which  show  by  way  of  example,  a  switch 
constructed  according  to  the  invention,  in  which: 
Figures  1  and  2  are.  front  elevations  of  part  of  a 


& 


switchboard  showing  the  switch  arms  for  the  two 
sets  of  resistances  in  varying  positions.  Figure  3 
is  a  part  and  elevation  of  Figure  2  seen  from  the  left. 
The  switchboard  1  is  provided  with  two  sets  of 


MOTION     PICTURE     PROJECTION 


55 


radially  disposed  contact  studs  2,  2a,  connected  in 
the  usual  manner  to  two  sets  of  resistances  (not 
shown  in  the  drawings).  Each  set  of  contact  studs 
is  provided  with  a  switch  arm  3,  3a,  pivotally  mount- 
ed on  the  switchboard  at  4,  4a,  respectively.  The 
switch  arm  3  has  pivoted  thereto  at  5  one  end  of  a 
connecting  member  6,  while  the  switch  arm  3a  has 
pivotally  connected  at  5 a  one  end  of  a  connecting 
member  6a. 

The  members  6  and  6a  are  connected  at  or  near 
their  inner  ends  by  a  pivot  7.  The  member  6  is 
provided  at  its  extreme  inner  end  with  a  backward 
projection  stop  8  located  in  such  a  manner  as  to 
engage  one  edge  or  side  of  the  member  6a,  while  the 


cr 


56  MOTION     PICTURE     PROJECTION 

member  6a  is  provided  at  its  inner  end  with  a  for- 
ward projecting  stop  8a  arranged  to  engage  one 
edge  of  the  opposite  member  6.  Each  of  the  switch 
arms  is  provided  with  an  operating  handle  9,  9a, 
secured  at  or  near  the  front  end  of  the  rotatably 
mounted  holders  10,  lOa,  respectively. 

The  operation  of  the  apparatus  is  as  follows: 
When  the  switch  arms  3,  3a,  are  in  the  position 
shown  in  Fig.  1,  both  are  in  the  zero  position  in 
which  no  current  is  passing  through  either  of  the 
resistances.  If  it  is  desired  to  switch  on  the  arc, 
connected  with  the  contact  studs  2,  the  switch  arm 
3  is  rotated  in  an  anti-clockwise  direction,  that  is, 
into  the  position  shown  in  full  lines  in  Fig.  2  in 
which  position  the  maximum  amount  of  current  is 
switched  on  in  one  circuit,  while  no  current  is  pass- 
ing in  the  other.  If  now  it  is  desired  to  switch  on  the 
current  in  the  circuit  connected  with  the  contact 
studs  2a,  the  switch  arm  3a  will  have  to  be  rotated  in 
a  clockwise  direction  as  will  be  readily  understood. 
The  stops  8,  8a,  on  the  inner  ends  of  the  members  6, 
6a,  are  so  arranged  that  the  maximum  movement  of 
the  switch  arms  is  reached,  when  for  instance,  one 
arm  is  moved  to  the  position  in  which  the  full  current 
is  allowed  to  pass  and  the  opposite  arm  is  in  zero 
position.  If  the  switch  arm  3a  is  now  rotated  in  a 
clockwise  direction,  the  opposite  arm  3  will  be  moved 
back  towards  its  zero  position,  to  a  corresponding 
extent  to  which  the  switch  arm  3a  is  advanced. 

If  it  is  desired  to  switch  on  full  current  in  the 
circuit  connected  to  the  contact  studs  2a,  the  switch 
arms  will  assume  the  position  shown  in  dotted  lines 
in  Fig.  2,  in  which  the  switch  arm  3  is  returned  to 
its  zero  position. 


MOTION     PICTURE     PROJECTION  57 


THE  STEP-DOWN  TRANSFORMER 

To  a  great  many  projectionists  the  working  prin- 
ciple of  a  transformer  is  a  mystery,  whereas  it  is  one 
of  the  simplest  electrical  devices  built. 

A  transformer  is  a  device  for  changing  the  voltage 
and  current  of  an  alternating  current  circuit. 

Transformers  are  spoken  of  as  Step-up  and  Step- 
down  transformers.  It  is  the  step-down  transformer 
that  is  used  for  motion  picture  work,  so  that  is  the 
one  we  shall  deal  with  in  this  article. 

Step-down  transformers  are  known  under  many 
trade  names  such  as  Economizers,  Inductors,  Com- 
pensarc's,  etc. 

The  three  essential  parts  of  a  transformer  are 
two  copper  coils  known  as  the  primary  and  second- 
ary, and  a  laminated  iron  core. 

The  core  of  the  transformer  is  made  up  of  a  num- 
ber of  thin  sheets  of  annealed  iron;  these  sheets  are 
very  thin,  generally  running  to  one-hundredth  part 
of  an  inch  in  thickness,  the  exact  thickness  depending 
upon  the  frequency  of  the  circuit  the  transformer  is 
to  be  used  on.  Each  of  the  sheets  is  given  a  coat 
of  some  insulating  compound,  so  that  they  are  in- 
sulated from  each  other.  The  sheets  are  then  built 
one  upon  the  other  in  the  form  of  a  hollow  square 
till  a  core  large  enough  is  obtained,  the  sheets  are 
then  clamped  together  and  are  insulated  with  mica 
or  some  other  insulating  material,  so  that  the  two 
copper  coils  may  be  wound  around  the  core  without 
the  copper  wire  of  the  coils  coming  in  contact  with 
the  iron  core.  Figure  1  is  a  diagram  of  an  element- 


58 


MOTION     PICTURE     PROJECTION 


ary  transformer,  showing  the  primary  coil  wound 
around  one  leg  of  the  core  and  the  secondary  coil 
wound  around  the  opposite  leg. 


Fig.  1 

When  we  close  the  circuit  on  the  primary  side  of 
transformer  the  current  passing  through  the  primary 
coil  magnetizes  the  iron  core,  this  magnetism  in 
turn  induces  an  A.  C.  current  in  the  secondary  coil. 
So  that  while  the  primary  and  secondary  coil  are 
insulated  from  the  core  and  from  each  other,  there 
is  a  magnetic  connection  between  both  coils  and  core. 

If  we  turn  back  to  the  basic  principle  of  induction 
the  working  principle  of  the  transformer  is  made 
clear. 

If  an  A.  C.  current  is  passed  through  a  conductor 
encircling  a  bar  of  soft  iron,  the  iron  will  become  a 
magnet  and  remain  so  just  as  long  as  current  is 
passed  through  the  conductor. 

If  a  bar  of  iron  carrying  a  conductor  around  it, 


MOTION     PICTURE     PROJECTION 


59 


be  magnetized  in  a  direction  at  right  angles  to  the 
plane  of  the  conductor  a  momentary  E.  M.  F.  will 
be  induced  in  the  conductor;  if  the  current  be  re- 
versed another  momentary  E.  M.  F.  will  be  induced 
in  the  opposite  direction  in  the  conductor. 

The  pressure  induced  in  the  secondary  coil  de- 
pends on  the  ratio  between  the  number  of  turns  in 
the  primary  and  secondary  coils.  Suppose  the  pri- 
mary coil  has  (50)  turns  of  wire  and  the  secondary 
(5)  turns,  there  would  be  a  transformation  ratio  of 
10  to  1,  so  if  the  primary  coil  was  supplied  with  cur- 
rent at  a  pressure  of  500  volts,  the  pressure  in  the 
secondary  coil  would  be  one-tenth  of  this  or  500-r- 
10=50  volts. 

Now  let  us  suppose  that  we  have  a  flow  of  20  am- 
peres in  the  primary  coil  and  that  the  ratio  is  the 
same  (10  to  1),  then  20X10=200  which  equals  the 
flow  of  current  in  the  secondary  coil. 

On  the  primary  coil  we  have  20  amperes  at  a  pres- 


SWITCH 


TRANSFORMER 
CONNECTIONS 
FOR    M.P.WORK 


Fig.  2 


60 


MOTION     PICTURE     PROJECTION 


sure  of  500  volts  or  500X20=10,000  Watts  or  10 
K.  W.  On  the  secondary  we  have  200  amperes  at  a 
pressure  of  50  volts  or  200X50=10,000  Watts  or 
10  K.  W.  So  we  see  that  the  wattage  on  the  pri- 
mary is  equal  to  the  wattage  on  the  secondary,  as- 
suming that  there  is  no  loss  in  transformation. 

We  know  that  there  are  two  forms  of  losses  in  all 
transformers,  the  iron  or  core  loss  and  the  copper 
or  coil  loss.  These  losses  total  about  10  per  cent. 
The  core  losses  are  going  on  as  long  as  the  switch  on 
line  side  of  the  transformer  is  closed ;  in  other  words 


Powers  Inductor  Connected  to  Two  Arc  Lamps 

while  the  transformer  is  carrying  a  no-load  current. 
The  copper  losses  only  take  place  while  the  arc  is 
burning  or  current  is  being  drawn  from  the  secon- 
dary coil. 

Let  us  suppose  the  primary  coil  is  drawing  20 
amperes  at  a  pressure  of  100  volts,  the  wattage  in 
the  primary  circuit  would  be  100X20=2,000  Watts. 
Let  us  assume  that  the  losses  in  transformation  is  10 
per  cent,  this  would  mean  that  the  wattage  on  the 
secondary  circuit  would  be  2,000  Watts  less  10  per 
cent  or  1,800  Watts. 

Transformers  should  always  be  connected  between 
the  machine  switch  and  the  arc  lamp,  so  that  when 


MOTION     PICTURE     PROJECTION  61 

the  machine  switch  is  pulled,  it  stops  a  no-load  cur- 
rent from  passing  through  the  primary  coil  of  the 
transformer. 

POINTS  TO  REMEMBER  ABOUT 
TRANSFORMERS 

Make  sure  that  the  primary  coil  (marked  line)  is 
connected  to  the  source  of  supply. 

See  that  transformer  is  connected  between  ma- 
chine switch  and  arc  lamp. 

Do  not  use  any  resistance  device  in  series  with  a 
transformer. 

Make  sure  that  all  the  connections  are  tight. 

Cover  all  line  terminals  on  transformer  with  tape. 

Place  transformer  away  from  metal  walls  of  booth. 

Keep  arc  short. 

See  that  voltage  and  cycles  marked  on  transformer 
corresponds  with  supply  voltage  and  cycles. 

THE  HALLBERG  ECONOMIZER 

The  Hallberg  economizer  is  simply  a  transformer 
of  the  semi-constant  current  type,  taking  A.  C.  cur- 
rent at  line  voltage  and  delivering  A.  C.  current  at 
arc  voltage.  Semi-constant  means  that  it  will  take 
the  line  current  at  a  fixed  potential  and  will  deliver 
from  the  secondary  a  steady  amperage  flow  regard- 
less of  the  length  of  the  arc. 

The  economizer  consists  of  a  continuous  rectangu- 
lar core,  on  one  leg  of  which  is  the  primary  winding, 
on  the  opposite  core  leg  is  the  secondary  which  is 
made  of  larger  cross  section  wire,  this  coil  is  con- 
nected to  lamp. 


62  MOTION     PICTURE     PROJECTION 


1 


Power's 
Inductor 


Hallberg 
Economizer 


MOTION     PICTURE     PROJECTION 


On  110  volts  the  economizer  line  wires  are  usu- 
ally attached  to  terminals  1  and  2  for  any  voltage 
from  100  to  105,  to  1  and  3  for  110  volts  or  to  1 
and  4  for  voltage  between  115  and  210. 


TO  LIU 


PIWC 


Some  operators  desire  varying  candle  power  at 
the  arc  lamp  to  accommodate  lighter  or  more  dense 
films ;  in  a  case  of  this  kind,  it  is  possible  to  simply 
install  a  three  pole  main  line  cut  out  (with  one  single 
fuse  plug)  connected  to  the  economizer.  By  placing 
the  plug  in  socket  No.  2,  a  heavy  amperage  is  ob- 


MOTION     PICTURE     PROJECTION 


tained.     Unscrew  plug  and  place  in  3  and  we  get  a 
medium  current,  and  if  we  place  plug  in  4  we  get 
the  lowest  amperage  possible.     This  gives  us  three 
degrees  of  amperage  at  arc.    By  installing  more  than 
one  fuse  at  a  time  we  would  blow  the  fuse,  as  this 
would  be  short-circuiting  the  primary  coil. 
When  using  the  Hallberg  economizer : 
1.  Place  economizer  at  least  12  inches  away  from 
sheet  iron  walls,  as  otherwise  there  will  be  a 
humming  noise. 


Showing  economizer  connections 
from  wall  switch  to  arc  lamp 


MOTION     PICTURE     PROJECTION 


65 


2.  30  amperes  line  fuses  are  large  enough  for  110 

volts  and  15  amperes  for  220  volts. 

3.  Connect  fuses,  switches   and  wires  exactly  as 
illustrated. 


66 


MOTION     PICTURE     PROJECTION 


4.  Make  sure  that  all  connections  are  tight,  espe- 

cially  at   the    carbon   clamps    in   the   lamp 
house. 

5.  Cover   all   line   terminals    on   economizer   with 

tape. 

6.  Use  only  %  inch  soft  carbons  cored. 

7.  Feed  carbons  often  and  a  little  at  a  time. 

8.  Keep  arc  short,  not  over  1/32  inch. 


Hallberg  Automatic  4-in-l  Regulator 
Connected  to  Mazda  Lamp 


MOTION     PICTURE     PROJECTION  67 


INSTRUCTIONS  FOR  INSTALLING  AND 

OPERATING  A-C.  TYPE  "A" 

COMPENSARC 

The  compensarc  is  a  self-contained  device  and  re- 
quires no  auxiliary  rheostat  or  other  controlling 
mechanism.  It  should  be  mounted  near  the  picture 
machine,  so  that  the  switch  is  convenient  to  the 
operator. 

Before  installing  the  compensarc  examine  the  name 
plate  to  see  if  the  rating  agrees  with  the  cycles  and 
line  voltage  of  the  circuit  from  which  it  will  operate. 
Connect  both  wires  from  the  operating  circuit  to 
the  two  terminals  marked  "line,"  and  from  the  two 
terminals  marked  "lamp"  connect  the  wires  leading 
to  the  terminals  of  the  picture  machine  lamp.  As 
this  is  an  alternating-current  device,  there  are  no 
positive  or  negative  wires. 

The  primary  or  line  wires  should  be  fused  with  a 
fuse  about  half  the  size  of  the  maximum  current  at 
the  lamp.  This  would  ordinarily  require  about  30- 
ampere  fuse. 

This  device  is  adjustable  in  three  steps,  which 
three  steps  have  been  found  to  meet  the  general  ser- 
vice conditions.  When  the  switch  is  open  no  current 
flows  through  the  lamp,  so  the  operator  can  freely 
take  out  the  carbons  and  make  any  adjustments  re- 
quired without  opening  the  line  switch. 

Throwing  the  switch  blade  in  contact  with  clip 
No.  1  gives  an  adjustment  so  that  with  the  carbons 
separated  about  3/16  in.  the  current  supply  is  ap- 


68 


MOTION     PICTURE     PROJECTION 


proximately  30  amperes,  which  gives  a  light  suitable 
for  light  films  or  a  short  throw.  In  contact  with 
clip  No.  2  the  adjustment  changes  so  that  approxi- 
mately 40  amperes  flow  through  the  lamp.  This  is 
the  usual  operating  position  of  the  compensarc 
switch  and  gives  a  powerful  white  light  which  is  found 
to  be  best  adapted  for  all  films. 


Fig.  1.     A-C.  Compensarc 


MOTION    PICTURE     PROJECTION  69 

Throwing  the  switch  blade  over  to  clip  No.  3  air 
lows  approximately  60  amperes  to  flow  through  the 
lamp.  This  gives  an  intense  light  and  is  required 
only  where  the  films  are  very  dense  or  the  throw  is 
very  long. 

The  alternating-current  compensarc  is  a  trans- 
former device  for  use  on  alternating-current  circuits 
which  cuts  down  the  current  supply  on  110-220 
volts,  with  the  voltage  required  at  the  arc  approxi- 
mately 35,  in  an  efficient  manner,  the  efficiency  being 
exceedingly  high  as  compared  with  the  rheostat, 
which  wastes  all  of  the  energy  between  110  and  35 
volts,  converting  this  energy  into  heat. 


Fig.  2.     Slate  Top  of  A-C.  Compensarc 
Showing  Switch  Blades 

• 

In  order  to  determine  if  your  compensarc  is  in 
good  condition  on  all  three  steps,  first,  start  an  arc 
on  any  one  of  the  steps,  then  jump  the  switch  quickly 
to  the  other  two  steps  in  succession,  watching  the 
light.  There  should  be  an  appreciable  difference  in 
the  light,  which  you  can  very  readily  detect  in  try- 
ing this  one  or  two  times. 

On  account  of  the  efficiency  of  the  compensarc 
there  is  so  little  energy  converted  into  heat  that  the 


70 


MOTION     PICTURE     PROJECTION 


outfit  can  be  installed  in  the  operating  room,  whereas 
it  would  be  impossible  to  do  the  same  with  the  rheo- 
stat. If  you  think  the  compensarc  is  heating  up, 
do  not  attempt  to  determine  the  temperature  with 
your  hand,  but  put  a  thermometer  on  it  on  the  hot- 
test part  for  about  five  or  ten  minutes,  and  then 
take  a  reading  of  the  thermometer.  Temperature 
rise  should  never  exceed  40  deg.  C.  or  72  deg.  F. 

If  you  will  observe  some  of  the  following  points, 
you  will  be  pretty  sure  to  get  good  results : 

1st — Make  sure  that  the  two  leads  marked  "lamp" 
are  connected  directly  to  the  lamp  of  the  picture 
machine.  It  is  not  necessary  to  select  for  positive  or 
negative  leads. 

2nd — The  other  two  cables  coming  from  the  com- 
pensarc should  be  connected  to  the  line  direct. 

3rd — Never  connect  any  resistances  up  with  the 
compensarc  on  either  the  lamp  or  the  line  side.  The 
compensarc  is  intended  to  cut  out  all  resistances.  Be 
sure  the  line  voltage  and  frequency  agree  approxi- 


TbFuse 
Block 
and 
Line, 
SWITCH 

Compensarc-^ 

r/c 
Lc 

1  U'    C    I' 

imp  —  x 

Line        Lamp 

99            99 

1 

Fig.  8.     Diagram  of  Connections  for 
A-C.  Compensarc 


MOTION     PICTURE     PROJECTION  71 

mately  with  the  line  voltage  and  frequency  marked 
on  the  name  plate  on  the  compensarc. 

4th — Be  sure  that  all  connections  from  the  line 
to  the  lamp  terminals  are  tightened  up  and  see  that 
the  switch  has  not  been  damaged  in  shipment.  In 
every  case  try  to  get  the  best  results  on  the  given 
current  that  you  possibly  can  by  focusing  the  arc  in 
relation  to  the  lens.  This  can  only  be  determined 
by  trial.  If  you  operate  the  arc  too  closely  to  the 
condenser  lens  you  are  apt  to  crack  it. 

Do  not  try  to  run  any  more  current  in  the  lamp* 
than  necessary  for  the  light  required.  A  %-in.  car- 
bon will  operate  very  satisfactorily  on  40  amperes, 
with  about  a  3/16  in.  separation.  Very  much  more 
current  than  this  will  tend  to  produce  noise  at  the 
arc.  This  noise  is  not  caused  by  the  compensarc, 
but  is  caused  by  the  alternating  current  in  the  arc 
and  will  be  present  no  matter  wh&t  kind  of  an  outfit 
is  used. 


Flexible  Armored  Cable.    Twin  Conductors 


72 


MOTION     PICTURE     PROJECTION 


A-C.  COMPENSARCS  IN  MULTIPLE 

In  cases  where  more  than  60  amperes  of  current 
is  desired  irr  connection  with  the  motion-picture  pro- 
jection, two  alternating-current  compensarcs  con- 
nected as  shown  in  Fig.  4  can  be  used  to  give  entirely 
satisfactory  service.  Two  standard  alternating-cur- 
rent compensarcs  connected  in  this  manner  can  be 
used  to  give  a  maximum  of  120  amperes  to  the  mo- 
tion picture  lamp.  Eight  values  of  current  ranging 
between  30  and  120  amperes  inclusive  can  be  secured 
by  this  connection. 


To  Fuse 
SLOCK  Axo 

LMS  SWITCH 

line.                 LAW 

\\         \ 

9 

?! 

\  I         I 

T 

r       s 

5           1 

Fig.  4.     Diagram  of  Connections  for  Use  of  Two 
A-C.  Conipensarcs  in  Multiple 


MOTION    PICTURE     PROJECTION 


MERCURY  ARC  RECTIFIERS 

An  apparatus  used  to  change  A.  C.  to  D.  C. 

Consists  of  a  glass  bulb  into  which  are  sealed  two 
iron  anodes  and  one  mercury  cathode  and  a  small 
starting  electrode. 

The  bulb  is  filled  with  mercury  vapor.     No  cur- 


J[    Mercury  Arc 
*|    Rectifier 
-I     Connections 


rent  will  flow  till  the  starting  electrode  resistance 
has  been  overcome  by  the  conization  of  the  vapor 
in  its  neighborhood.  To  accomplish  this,  the  voltage 


74 


MOTION     PICTURE     PROJECTION 


Tube  — 


in  King  Coil 

•Starting  /inoafK 

ffe/oy 


_5er/es  Underload  j 
. Current^  Limiting  , 


Current  Limiting  \ 

Potential  Relay  1 


•    /regulating 
Reactance 


—Mam  ff&actonce 


Front  and  back  view  of  mercury  rectifiers 


MOTION     PICTURE     PROJECTION  75 

is  raised  sufficiently  to  cause  the  current  to  jump 
the  gap  between  the  mercury  cathode  and  the  start- 
ing cathode,  or  by  bringing  the  cathode  and  starting 
electrode  together  in  the  vapor  by  tilting  and  then 
separating  them,  thus  drawing  out  the  arc.  When 
this  has  been  done  current  will  flow  from  the  anode 
to  the  mercury  cathode  and  not  in  the  reverse  direc- 
tion. In  order  to  maintain  the  action  a  lag  is  pro- 
duced in  each  half  wave  by  the  use  of  a  reactive  or 
sustaining  coil,  hence  the  current  never  reaches  its 
zero  value  otherwise  the  arc  would  have  to  be  re- 
started. 


ARC 


VOLTMETER     CONNECTED    IN   MULTIPLE 
AMMETER     CONNECTED    IN    SERIES 


76 


MOTION     PICTURE     PROJECTION 


THREE-WIRE  SYSTEM 

A  system  of  wiring  for  current  distribution  where 
three  wires  are  used  in  place  of  two  sets  of  two 
wires.  The  advantage  of  the  system  is  the  saving 
of  copper  and  consequently  the  cost  of  wiring.  By 
means  of  the  three-wire  system  we  are  able  to  in- 
crease the  pressure  at  which  the  current  is  transmit- 
ted, and  take  advantage  of  the  greater  efficiency  of 
the  lower  voltage  lamps. 

A  conductor  rated  to  carry  a  current  of  20  am- 


/-?. 


Fic  1. 


MOTION     PICTURE     PROJECTION 


77 


peres,  can  carry  that  20  amperes  at  a  pressure  of 
10  volts  o-r  10,000  volts,  and  as  electrical  energy 
is  equal  to  the  amount  of  current  multiplied  by  the 
voltage,  it  will  readily  be  seen  that  the  transmitting 
capacity  of  a  current  can  be  greatly  increased  by  in- 
creasing the  voltage  without  increasing  the  size  of 
the  conductor.  However,  incandescent  lamps  are 
usually  made  for  use  on  a  pressure  of  110  volts,  so 
it  would  be  necessary  to  either  cut  down  the  voltage 
to  this  pressure  or  connect  a  number  of  the  lamps 
in  series  to  take  care  of  the  extra  pressure. 

Fig.  1  shows  two  110  volt  dynamos  A  and  B  sup- 
plying two  independent  circuits.     In  each  case  five 


( 


>  ito 


Fie  £. 


78 


MOTION    PICTURE     PROJECTION 


110  volt  y2  ampere  lamps  are  connected  across  a 
110  volt  circuit,  each  dynamo  supplying  2^  am- 
peres at  a  pressure  of  110  volts;  which  means  a 
total  wattage  of  550  W.  for  the  ten  lamps.  Fig.  2 
shows  us  the  same  two  dynamos,  now  connected  to- 
gether in  series,  and  the  same  ten  lamps,  this  time 
connected  in  series  of  pairs  across  a  potential  of  220 
volts  (on  account  of  the  dynamos  being  connected 
in  series).  As  the  voltage  in  this  case  is  just  double 
each  lamp  now  draws  14  ampere  instead  of  %  am- 
pere as  in  Fig.  1  which  makes  the  wattage  in  this 
case  220  X  2%  =  550  watts,  thus  the  wattage  in 
each  case  is  the  same,  but  in  Fig.  2  we  have  made  a 
saving  of  100  per  cent,  in  copper,  as  we  used  two 
wires  only,  against  four  in  Fig.  1. 


i 

o 


1 

O 


I 

o 


FIQ.  5. 


MOTION    PICTURE     PROJECTION 


79 


The  arrangement  in  Fig.  2  is  open  to  objection, 
however,  as  should  one  of  the  lamps  burn  out  or  be 
turned  off,  its  companion  will  also  go  out.  This  is 
overcome  in  the  three  wire  system  by  introducing  a 
third  wire  into  the  circuit  (Fig.  3)  thus  providing 
a  supply  or  return  wire  to  any  of  the  lamps  and 
permitting  any  of  the  lamps  to  be  cut  out  of  the 
circuit  without  affecting  any  of  the  others. 

The  three  wire  system  is  generally  obtained  by 
connecting  two  dynamos  of  a  like  capacity  in  series 
and  connecting  a  third  or  neutral  wire  to  a  point 
common  to  both  dynamos.  The  dynamos  being  con- 
nected in  series,  we  get  the  added  voltage  of  the 
dynamos  when  connected  between  the  two  outside 


V- 

05 


O 


O  O   0 


\  o 


FIG  $. 


80 


MOTION     PICTURE    PROJECTION 


wires,  and  the  voltage  of  one  dynamo  only  when  con- 
nected between  either  of  the  outside  wires  and  the 
neutral  (Fig.  3). 

No  current  will  flow  over  the  neutral  wire,  if  the 
system  is  kept  balanced  (the  same  amount  of 
amperage  is  drawn  off  either  side  of  the  system) 
and  the  flow  of  current  in  the  neutral  wire  at  any 
time  is  the  difference  between  the  amperage  drawn 
from  either  side. 

Fig.  4  shows  a  three  wire  system,  A  and  B,  being 
two  110  volt  dynamos  connected  in  series,  C  is  the 
positive  wire,  D  the  neutral  wire  and  E  the  nega- 
tive wire.  The  ten  circles  on  either  side  of  the  neu- 
tral wire  represent  lamps,  each  taking  one  ampere, 
as  we  have  the  same  amount  of  current  (10  amperes) 


r 


MOTION     PICTURE     PROJECTION 


81 


drawn  off  either  side,  the  system  is  balanced  and 
there  is  no  flow  of  current  in  the  neutral  wire.  The 
ten  amperes  being  drawn  from  dynamo  A  over  posi- 
tive wire  C  and  after  passing  through  the  lamps  re- 
turning to  dynamo  B  by  way  of  negative  wire  E. 

An  unbalanced  three  wire  system  is  shown  in  Fig. 
5,  taking  it  for  granted  that  each  of  the  lamps  is 
taking  one  ampere,  we  have  four  amperes  on  one 
side  and  six  on  the  other,  6  —  4  =  2,  so  our  system 
is  unbalanced  to  the  extent  of  two  amperes,  and  this 
represents  the  flow  of  current  in  the  neutral  wire. 
Four  amperes  being  drawn  from  dynamo  A  over 
positive  line  C  then  after  passing  through  the  four 
lamps  on  the  upper  side,  the  four  amperes  goes  to 
feed  four  of  the  lamps  on  the  lower  side,  but  as  there 


I 


j 


T 

\ 
0 


t 

o 

i 


FIG.  b. 


MOTION    PICTURE    PROJECTION 


are  six  lamps  to  feed  on  the  lower  side,  the  two  extra 
amperes  are  drawn  from  dynamo  B  over  neutral 
wire  D  (which  under  the  circumstances  acts  as  a 
positive).  So  in  Fig.  5,  we  have  four  amperes  flowing 
from  dynamo  A  over  positive  line  C,  two  amperes 
flowing  from  dynamo  B  over  neutral  wire  D,  and  six 
amperes  flowing  to  dynamo  B  over  negative  line  E. 

In  Fig.  6  we  have  another  unbalanced  system,  in 
this  case  six  amperes  are  drawn  from  dynamo  A  over 
positive  line  C  and  after  feeding  the  six  lamps  on 
the  upper  side,  four  amperes  are  used  to  feed  the 
four  lamps  on  the  lower  side,  the  two  extra  amperes 
going  back  to  dynamo  A  over  the  neutral  wire  D 
(which  now  acts  as  a  negative)  and  four  amperes 
going  to  dynamo  B  over  negative  line  E. 

With  a  three  wire  system,  the  idea  is  to  keep  the 
system  as  near  balanced  as  possible.  For  motion 
picture  work  it  is  advisable  to  connect  the  machines 
between  the  neutral  wire  and  the  outside,  one  ma- 
chine on  each  side  of  the  system.  When  using  the 
positive  and  neutral  wires,  the  positive  goes  to  the 
top  jaw  of  arc  lamp  and  the  neutral  to  the  lower, 
if  you  use  the  neutral  and  negative  wires  then  the 
neutral  wire  goes  to  top  jaw  of  arc  lamp  and  the 
negative  to  the  lower. 


MOTION     PICTURE     PROJECTION 


83 


FUSES 

A  safety  device  used  on  your  line  to  protect  the 
circuit. 

A  short  length  of  fusable  wire  introduced  in  a  cir- 
cuit so  that  if  the  temperature  of  circuit  should  rise 
above  the  rated  capacity  of  fuse  the  wire  will  melt 
and  thereby  open  the  circuit. 

Fuses  are  made  in  different  shapes  and  sizes,  the 
moving  picture  operator,  however,  will  only  be  called 
upon  to  handle  the  under-mentioned. 


Copper-Tipped  Fuse  Link 

Link  Fuse.  The  link  fuse  is  the  fuse  always  used 
in  the  booth,  being  of  the  open  type  it  cannot  be 
readily  boosted  without  same  being  plainly  seen. 


Enclosed  or  "Cartridge"  Fuse 


Section  of  Enclosed  Fuse 


84  MOTION     PICTURE     PROJECTION 

Link  fuses  have  no  protective  covering,   so   should 
always  be  installed  in  a  metal  cabinet. 

Cartridge  Fuse.  Made  by  connecting  two  metal 
cap  terminals  with  a  short  paper  tubing.  The  two 
metal  caps  are  connected  by  a  thin  wire  which  runs 
through  the  paper  tubing,  the  tubing  is  filled  with 
some  non-conducting  powder. 

Plug  Fuses.  Plug  fuses  are  used  for  protecting 
the  house  wiring  and  circuits  carrying  small  amper- 
age. 

In  fusing  upon  any  circuit  you  must  take  into  con- 
sideration the  size  of  the  wire  used  and  the  amount 
of  amperage  to  be  drawn.  The  fuse  should  be  rated 
under  the  carrying  capacity  of  the  wire  with  a  suf- 
ficient margin  to  allow  the  required  number  of  am- 
peres to  pass  over  without  overheating.  The  rating 
of  all  fuses  is  marked  on  them.  Never  use  a  fuse  not 
marked. 


Edison  Fuse-Plug 


MOTION     PICTURE     PROJECTION  85 


TESTING  FOR  GROUNDS 

Always  remember  that  like  poles  repel  each  other 
while  unlike  poles  attract  each  other,  in  other  words 
the  negative  polarity  is  attracted  by  the  positive 
polarity,  and  vice  versa,  while  the  negative  has  no 
attraction  for  negative  nor  the  positive  for  positive. 

The  positive  wire  of  one  system  will  have  no  at- 
traction for  the  negative  wire  of  any  other  system  4 
except  its  own,  nor  will  the  negative  of  one  system 
find  any  attraction  in  the  positive  of  any  other  sys- 
tem. 

A  ground  is  merely  the  current  from  one  polarity 
being  attracted  by  the  opposite  polarity,  through 
the  ground  or  some  conducting  medium  other  than 
that  in  the  circuit. 

Supposing  that  we  are  working  on  a  three 
wire  system  and  our  neutral  wire  is  grounded,  and 
that  we  take  and  connect  one  of  the  outside  wires  to 
the  upper  jaw  of  arc  lamp,  and  we  connect  the 
neutral  wire  to  the  lower  jaw  (the  neutral  wire  now 
acts  as  negative  to  the -upper  or  positive  wire).  We 
now  ground  the  machine  by  connecting  the  metal 
framework  of  machine  to  the  conduit  coming  in 
booth.  Our  machine  now  becomes  grounded  on  the 
neutral  because  we  have  made  contact  between  the 
frame  of  machine  and  the  already  grounded  conduit. 
Should  we  now  connect  our  test  lamp  between  the 
upper  jaw  of  arc  lamp  and  frame  of  machine  or  lamp 
house  we  will  naturally  get  a  light  as  we  are  con- 
nected between  the  two  polarities  of  the  system. 


86  MOTION     PICTURE     PROJECTION 

Now  should  the  arc  lamp  become  grounded  (  caused 
we  will  say  by  the  mica  insulation  coming  out  of  jaw 
connection)  on  the  lower  jaw  it  would  mean  that  the 
system  is  grounded  on  the  negative  polarity  and  the 
arc  itself  is  grounded  on  the  negative  polarity,  and 
this  may  or  may  not  blow  the  fuse.  But  should  it 
be  the  upper  jaw  of  lamp  that  becomes  grounded 
then  our  arc  would  be  grounded  on  the  opposite  po- 
larity to  that  of  the  machine,  and  thus  cause  a  short 
circuit. 

•  To  test  for  a  ground  in  the  lamp  house,  first  dis- 
connect the  ground  wire  and  connect  the  terminals 
of  test  lamp  between  the  upper  and  lower  carbons. 
We  should  now  get  a  light,  as  we  are  connected  be- 
tween both  polarities,  this  test  merely  shows  that  we 
have  current  in  our  lamp. 

Connect  the  test  lamp  between  the  upper  car- 
bon and  the  frame  of  lamp  house,  if  we  get  a  light 
then  our  lower  jaw  is  grounded,  if  we  do  not  get  light 
then  take  it  for  granted  that  lower  is  free  from 
grounds. 

Next  test  to  see  if  the  upper  is  grounded  by  con- 
necting the  test  lamp  between  the  lower  jaw  of  arc 
lamp  and  the  frame  of  lamp  house,  if  we  get  a  light 
then  upper  jaw  is  grounded.  Always  find  the  cause 
of  ground  and  remove  same  at  earliest  opportunity. 

Before  using  the  test  lamp  see  that  lamp  is  alright 
and  that  it  makes  good  contact  in  socket. 

To  test  for  a  ground  in  the  rheostat,  use  a  bell  set. 
First  connect  the  terminals  of  bell  set  between  the 
two  binding  posts  of  rheostat,  and  if  rheostat  is  free 


MOTION     PICTURE    PROJECTION  87 

from  open  circuits  you  should  get  a  ring,  next  con- 
nect the  terminals  of  bell  set  between  one  of  the  coils 
or  plates  in  rheostat  and  the  iron  frame,  if  you  get 
a  ring  it  signifies  that  the  rheostat  is  grounded,  but 
this  test  will  not  tell  you  which  coil  or  plate  is  caus- 
ing the  ground.  To  find  exactly  where  ground  is, 
proceed  as  follows :  connect  bell  set  between  the  first 
coil  and  frame,  if  you  get  a  ring,  disconnect  the  first 
coil,  now  connect  between  the  second  coil  and  frame, 
if  you  get  a  ring  disconnect  the  second  coil,  and  do 
the  same  to  third  and  fourth  coil,  keep  testing  in 
this  manner  till  bell  stops  ringing,  then  the  coil  you 
removed  last  was  the  coil  that  was  grounded,  so  if 
you  have  removed  six  coils  and  the  bell  stops  ringing 
when  connected  between  the  seventh  coil  and  frame, 
it  was  coil  number  six  that  was  grounded. 

If  the  rheostat  is  made  of  more  than  one  section, 
test  each  section  separately  and  find  which  section 
the  ground  is  in,  then  proceed  as  above.  This  is  to 
save  time. 


88 


MOTION     PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  89 


THE  PROJECTION  ROOM 

The  room  should  contain  everything  necessary  for 
perfect  projection,  but  nothing  that  can  be  done 
without.  Nothing  but  the  projection  of  films  should 
be  done  in  the  room,  an  ante-room  should  be  provided 
with  work  bench  and  rewinder.  The  room  should  be 
large  enough  to  permit  the  free  movements  of  the 
operator  or  operators  and  should  contain  the  neces- 
sary closets  and  shelves  for  the  operators'  clothes, 
tools,  supplies,  etc. 

The  operator  should  see  that  he  has  sufficient  sup- 
plies, such  as  fuses,  lugs,  film  cement,  asbestos  cable, 
condensers,  various  lubricants,  carbons,  mica, 
brushes  for  motor,  belting  and  a  few  of  the  necessary 
parts  for  machine  to  replace  those  parts  that  are 
liable  to  need  replacing  owing  to  wear,  etc. 

The  operator  should  carry  a  kit  of  tools  that  will 
permit  him  to  do  any  repair  work  that  he  may  be 
called  upon  to  do,  the  manager  of  today  has  very 
little  use  for  the  would-be  operator  who  shows  up 
on  the  job  with  a  ten  cent  pair  of  pliers  and  a  piece 
of  string. 

If  using  rheostats  then  same  should  be  installed 
outside  the  projection  room,  but  the  control  handles 
should  be  placed  so  that  they  are  within  easy  reach 
of  the  projectionist,  without  his  having  to  leave  the 
machine.  The  operator  will  thus  find  working  con- 
ditions a  whole  lot  more  comfortable. 

All  openings  such  as  projection  holes  and  port 
holes  must  be  so  equipped  with  shutters  that  they 
will  all  close  automatically  in  case  of  fire. 


90 


MOTION     PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  91 

A  lot  could  be  said  about  the  position  of  booth  and 
the  construction  of  same,  but  the  trouble  is  that  the 
operator  is  generally  the  last  man  a  manager  or  ex- 
hibitor will  consult  in  this  matter  when  planning  the 
theatre,  so  the  operator  has  to  work  under  conditions 
as  he  finds  them. 

One  thing  we  would  advise  and  that  is,  that  the 
walls  of  the  booth  should  be  painted  a  flat  black  (if 
same  has  not  been  done).  The  size  of  all  openings 
should  be  reduced  as  much  as  possible,  shade  all 
lights  so  that  none  of  the  light  finds  its  way  into  the 
auditorium  of  the  theatre. 

Each  operator  naturally  has  his  own  idea  as  to 
just  what  constitutes  an  ideal  projection  room, 
however,  we  are  submitting  in  the  following  pages 
a  detailed  description  of  the  furnishings  and  fittings 
of  two  well  known  and  much  discussed  projection 
rooms  in  New  York  City. 


92 


MOTION     PICTURE     PROJECTION 


PLAN  vitw  OF  lUwmo,  PKOJCCTICN  AND  Moron  GENERATOR  ROOM 
jf»Tt  AU.  WAi.it  „  r  c  «/tfcx  AM««Mr(/rco.. 


Booth  Plan,  Reo  Theatre,  New  York  City 


MOTION     PICTURE     PROJECTION 


MCTKIW-X  ..  BEVELED  E06£ 


Plan  for   Single   Machine   Booth 


94 


MOTION     PICTURE     PROJECTION 


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MOTION     PICTURE     PROJECTION 


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96 


MOTION    PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  97 


AN  IDEAL  PROJECTION  ROOM 

"The  largest  theatre  in  the  world,"  the  New  York 
Capitol,  has  a  projection  room  in  keeping  with  the 
rest  of  its  luxurious  appointments.  The  projection 
room  proper  is  41  feet  long  and  19  feet  deep  and  as 
will  be  seen  by  the  accompanying  photographs,  it  is 
furnished  with  everything  necessary  for  perfect  pro- 
jection. Four  of  the  latest  Type  S  Simplex  ma- 
chines are  responsible  for  the  projection,  each  ma- 
chine is  equipped  with  an  automatic  arc  control  and 
a  metal  cabinet  for  receiving  hot  carbon  stubs. 

There  is  also  a  special  spotlight  and  a  Simplex 
Stereopticon,  the  spotlight  is  fitted  with  an  8-inch 
iris  diaphragm  so  constructed  and  arranged  that 
any  sized  spot  can  be  immediately  obtained,  it  is  also 
fitted  with  a  curtain  dissolve  which  allows  the  oper- 
ator to  gradually  flood  or  dim  the  stage  for  special 
lighting  effects,  and  dispenses  with  the  troublesome 
masks. 

Current  supply  is  D.  C.  through  50-125  multiple 
unit  rheostats.  The  rheostats  are  placed  in  a  special 
room  adjoining  the  projection  room,  the  rheostat 
controls  being  on  the  front  wall  near  each  projector 
within  easy  reach  of  the  operator.  Each  machine 
draws  125  amperes  at  an  approximate  pressure  of 
68  volts. 


98  MOTION     PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  99 

The  firing  for  the  projectors  is  brought  under 
the  floor  up  through  the  machine  pedestals  and  then 
to  machine  switch.  Cool  and  comfortable  working 
conditions  are  assured  at  all  times,  the  room  having 
4  windows  opening  directly  into  the  street  besides 
two  24-foot  exhaust  fans ;  a  vent  pipe  runs  from 
the  lamp  house  of  each  projector  to  the  open  air. 

At  the  far  end  of  the  projection  room  is  the  re- 
wind room,  here  are  found  a  specially  built  film  vault 
for  the  storage  of  film,  an  enclosed  motor  rewind 
equipped  with  an  automatic  stopping  device  in  case 
the  film  should  break  in  the  course  of  rewinding.  The 
comfort  of  the  projectionists  has  not  been  over- 
looked. An  up-to-date  washroom  and  lavatory  to- 
gether with  a  rest  room  for  their  special  use  adjoins 
the  projection  room. 

The  throw  is  197  feet  and  the  picture  is  projected 
on  one  of  Robins'  special  white  screens.  The  projec- 
tion of  the  pictures  and  the  musical  score  are  syn- 
chronized through  the  medium  of  the  Robins  speed 
indicators. 


100  MOTION     PICTURE     PROJECTION 


PROJECTION  ROOM  INTERNATIONAL 
CINEMA  QUIPMENT  CENTER 

The  projection  room  is  20  feet  long  by  10  feet 
deep  by  11  feet  in  height.  It  is  built  of  6-inch  hol- 
low tile,  plastered  on  both  sides.  Floor  is  arched 
reinforced  cement  with  2-inch  covering  of  red  on  the 
top,  which  renders  the  booth  neat  in  appearance  and 
easily  kept  clean. 

Placed  in  the  bottom  of  the  booth  are  four  11 
by  16-inch  openings  covered  with  fine  mesh  screen 
providing  fresh  air  intake.  An  18  by  24-inch  vent 
flue  leading  to  the  outside  carries  away  the  warm  air. 
This  flue  has  a  double  opening  in  the  booth,  one 
which  is  covered  by  a  grill,  and  in  the  other  open- 
ing is  placed  an  electric  ventilating  fan,  which  is 
controlled  through  the  switchboard.  By  arranging 
the  exhibits  in  this  manner  it  does  not  impede  the 
free  passage  of  air. 

There  are  eight  openings  in  the  booth.  Each  is 
protected  by  the  International  Fire  Shutter  System, 
which  consists  of  kalomein  frames  built  into  the  wall 
with  channel  iron  slideways  attached  into  which  are 
fitted  l/^-inch  asbestos  fire  shutters.  The  shutters 
are  suspended  by  chains  with  fuseable  links  from  a 
pipe  which  runs  along  the  front  wall  of  the  booth, 
and  is  controlled  by  gravity  when  a  fuse  melts  and 
releases  a  string,  the  weight  turns  the  pipe  and  drops 
all  shutters. 

The  fire  shutter  is  very  nea"t  in  appearance  and 
extremely  effective. 


MOTION     PICTURE     PROJECTION  101 

There  are  two  indirect  fixtures  in  the  booth  which 
are  controlled  by  push  button  placed  adjacent  to 
the  entrance  of  the  booth.  About  12  inches  from 
the  front  wall  of  the  booth,  and  directly  in  front  of 
each  machine,  is  a  drop  light  with  a  Crescent  lamp 
guard  and  porcelain  socket.  The  lighting  of  the 
booth  is  all  on  direct  current. 


Fig.  1 

There  is  a  signal  telegraph  controlled  from  the 
review  desk  in  the  interior  of  the  theatre  and  a  return 
call  system ;  also  an  extension  Bell  telephone  con- 
necting with  the  main  switchboard  of  the  Interna- 
tional Cinema  Quipment  Centre.  For  the  storage  of 


102  MOTION     PICTURE     PROJECTION 

film  during  the  course  of  projection  the  two  15-inch 
5-section  Safe-T-First  cabinets  are  used. 

Directly  in  the  rear  of  the  booth  is  a  large  kalo- 
mein  bench  6  feet  long  by  18  feet  wide,  which  is  used 
as  a  rewinding  table,  and  the  lower  portion,  which 
is  divided  into  drawers,  is  used  for  accessories  and 
supplies. 


Fig.  2 

There  is  also  provided  an  automatic  sprinkler 
system  in  the  booth,  fire  extinguishers  and  pails. 

The  electric  service  consists  of  110/220  volt  Edi- 
son D.  C.,  110/220  volt  single  phase  60  cycle  A.  C. 
and  220  volt  two  phase  A.  C.  This  power  is  supplied 
direct  from  the  lighting  company  on  a  special  service 


MOTION     PICTURE     PROJECTION  103 

run  from  the  basement.  Directly  behind  the  ma- 
chines in  the  rear  wall  of  the  operating  room  is  a 
special  control  board  designed  by  J.  E.  Robin.  This 
board  is  6  feet  square  of  a  dead  face  type.  All 
meters  and  switches  operate  from  the  front  and  are 
back  connected.  The  board  is  built  of  blue  Vermont 
marble  2  inches  in  thickness. 

Fig.  3  shows  the  appearance  of  the  front  and  Fig. 
4  the  rear.  On  the  face  of  the  board  are  mounted 
two  Weston  D.  C.  ammeters,  two  Weston  A.  C.  am- 
meters and  one  Weston  D.  C.  and  one  Weston  A.  C. 
volt  meters.  The  six  hand  wheels  directly  under- 
neath the  meters  control  volt  and  ammeter  switches, 
rendering  it  possible  to  read  the  amperage  or  voltage 
on  either  side  of  the  line,  or  the  arc,  and  on  any 
control  device  being  tested.  Each  D.  C.  ammeter  is 
provided  with  five  interchangeable  shunts,  and  each 
A.  C.  ammeter  with  three  current  transformers, 
which  are  shown  to  the  left  of  the  photograph  Fig.  4. 
The  A.  C.  ammeter  has  a  push  button  underneath  in 
the  circuit  which  is  connected  with  a  multiplier  to 
permit  reading  on  the  low  voltage  of  transformer. 
The  two  other  hand  wheels  shown  on  the  left  are  on 
the  right  side  of  the  booth  control  field  rheostat,  and 
the  upper  row  of  switches  machine  motor  circuits 
and  lighting,  vent  fans  and  Mazda  lamp  A.  C.  trans- 
formers. The  lower  row  are  the  four  main  line 
switches — two  provided  for  the  generator  switch- 
board and  two  for  the  engines. 

As  shown  on  photograph  Fig.  4 — 12-200  ampere 
Kleigl  plugging  pockets.  These  are  underneath  the 
front  of  the  board  and  underneath  the  booth  directly 
from  each  projecting  machine  is  run  in  conduit,  con- 


104 


MOTION     PICTURE    PROJECTION 


cealed  in  the  floor  two  No.  0  wires,  which  come  out 
through  a  furrel  in  the  bottom  of  the  board,  of 
which  there  are  four,  and  terminate  in  five-foot  long 
generator  cable  with  a  Kleigl  plug  attached. 

Directly  underneath  the  projecting  machine  in  the 
booth  is  a  ventilator,  where  are  located  A.  C.  arc 
transformers,  A.  C.  Mazda  transformer,  D.  C.  and 
A.  C.  rheostat  and  D.  C.  Mazda  lamp  rheostat.  All 


Fig.  3 


MOTION     PICTURE     PROJECTION  105 

connections  from  these  devices  run  direct  from  the 
main  switchboard  and  terminate  in  the  box  of  main 
switchboard.  It  is  possible,  therefore,  by  plugging 
in  one  of  the  four  machines  into  the  pockets  to  oper- 
ate on  the  different  kinds  of  apparatus  either  A.  C. 
or  D.  C.,  running  one  or  four  machines  simulta- 
neously. 

All  wiring  of  conduits  are  concealed  in  the  floor 
and  walls  of  the  booth,  and  the  wires  leading  to  the 
machines,  meters  and  arc  switch  come  up  directly  in 
the  centre  of  pedestal.  Set  flush  in  the  wall  directly 
underneath  the  lookout  hole  in  front  of  each  pro- 
jector is  a  special  control  panel  board  of  blue  Ver- 
mont marble  with  a  volt  meter  and  ammeter  mounted 
on  the  face  of  the  same,  and  Robin  Cinema  electric 
speed  indicator.  There  is  also  provided  a  radial 
rheostat  switch  connected  to  the  multiple  unit  rheo- 
stat. This  switch  is  used  to  control  the  amperage 
at  the  arc  which  may  be  run  from  5  to  100  amperes. 
This  marble  cover  on  panel  board  is  arranged  with 
hinges  to  open  down  into  the  booth,  thus  rendering  it 
accessible. 

In  addition  to  the  general  booth  equipment  there 
is  shown  to  the  rear  of  the  booth  in  photograph  the 
motor  generator  testing  department.  In  this  space 
are  five  different  types  of  motor  generators,  both 
single  and  two  phase,  with  special  panel  board  in 
front  of  each  one  with  control  switches  and  instru- 
ments. 

Each  generator  is  mounted  on  an  iron  pan,  which 
is  attached  to  frame  and  rests  on  cork  and  rubber 
to  prevent  noise  when  in  operation.  The  top  of  the 
platform  is  covered  with  a  battleship  linoleum  bound 


106 


MOTION     PICTURE     PROJECTION 


with  brass.  The  switchboard  shown  in  the  centre 
controls  the  motor  generator  sets,  and  is  intercon- 
nected with  the  main  switchboard  in  the  booth.  This 
board  is  also  dead  type  with  the  front  of  the  blue 
Vermont  marble  of  2-inch  thickness,  with  all  switches 
back  connected  and  enclosed  with  a  steel  cabinet  with 
two  doors  making  it  accessible  from  the  rear.  On 
the  upper  row  are  instruments  consisting  of  two  two- 


Fig.  4 


MOTION     PICTURE     PROJECTION  10T 

phase  Weston  indicating  watt  meters,  one  Weston 
single  indicating  watt  meter.  This  serves  to  show 
the  wattage  used  in  running  the  various  machines. 
The  two  lower  machines  are  without  meters,  which 
are  connected  across  the  two,  coming  out  of  the  bot- 
tom of  the  board,  which  indicate  in  watts  the  power 
being  taken  in  any  of  the  generators.  In  this  man- 
ner the  current  being  used  can  easily  be  determined. 
The  voltage  and  amperage  may  be  obtaind  from  the 
meters  on  the  individual  panel  or  from  the  interior 
of  the  instruments  in  the  booth. 

There  are  10  plugging  pockets  on  the  board,  two 
being  connected  with  each  machine.  The  two  cables 
shown  coming  out  of  the  board  connect  with  the 
main  switchboard  in  the  booth.  It  is  possible,  there- 
fore, to  plug  one  or  two  arcs  on  any  of  the  genera- 
tors or  for  comparative  test  to  run  two  generators 
simultaneously  with  one  arc  on  each. 

This  switchboard  contains  both  current  trans- 
formers, voltmeter  multipliers  and  resistances  and 
other  necessary  switches,  cutouts  and  accessories. 

The  machines  consist  of  two  Type  "S"  Simplex — 
one  Simplex  Mazda  equipment  with  A.  C.  and  D.  C. 
regulator  and  one  Simplex  with  1J^  to  1  shutter — 
5  to  1  movement  and  Argus  sheck  adapter.  This 
machine  is  also  equipped  with  Feaster  non-rewind. 
All  projectors  are  enameled  battleship  gray  with  fit- 
tings in  nickel.  Each  machine  is  equipped  with  volt 
and  ampere  meters  on  front  panel,  also  Robin  Cinema 
electric  speed  indicators,  lamp  house  with  Simplex 
arc  periscope,  which  throws  the  image  of  the  arc  on 
the  walls  or  ceiling.  The  Mazda  lamp,  A.  C.  trans- 
formers and  D.  C.  rheostats  are  located  in  the  floor 


108 


MOTION    PICTURE    PROJECTION 


of  the  booth,  and  are  controlled  from  the  interior  by 
hand  wheels  somewhat  similar  to  those  used  in  the 
pilot  house  aboard  ship. 


Figs.  5  and  6 


MOTION     PICTURE     PROJECTION 


109 


110 


MOTION     PICTURE     PROJECTION 


lit 

I 


MOTION    PICTURE     PROJECTION 


111 


Floor  Plan 

Orchestra  and  Balcony 

Visual  Screens  and  Projection  Angles.     Modern  Theatre  Pro- 
jection Layout  to  Determine  Size  and  Position  of  Screen  and 
Height  Above  Stage. 


112 


MOTION     PICTURE     PROJECTION 


LONGITUDINAL  SECTION 


t 


Floor  Plan,  Single  Floor  Theatre 


MOTION     PICTURE     PROJECTION  113 


WORKING  PRINCIPLE  OF  ELEMENTARY 
PROJECTION  MACHINE 

By  turning  the  operating  crank  A,  counter  clock- 
wise, the  main  shaft  B,  is  driven  through  the  4  to  1 
reduction  chain  drive  Z>,  a  steady  turning  motion 
being  caused  by  the  fly  wheel  C,  this  in  turn  operates 
the  upper  steady  feed  sprocket  E,  through  the  4  to  1 
reduction  gear  F,  thus  the  teeth  of  E  sprocket  which 
mesh  with  the  perforations  in  the  film,  feed  the  film 
at  a  constant  rate,  the  film  being  held  against  E  by 
pressure  roller  G.  A  film  loop  or  length  of  loose 
film  is  thus  maintained  between  E  and  the  steady 
drum  H.  The  film  is  fed  past  the  film  gate  inter- 
mittently by  the  intermittent  sprocket  /,  operated 
by  the  Geneva  movement  K,  the  latter  producing  a 
quick  quarter  turn  of  7,  followed  by  a  relatively  long 
rest  during  which  the  main  shaft  B  makes  one  revo- 
lution. The  barrel  shutter  L,  by  a  2  to  1  gear  with 
the  main  shaft  and  proper  timing,  operates  to  cut 
off  the  light  rays  from  the  screen  during  each  move- 
ment of  the  intermittent  sprocket  /,  and  to  admit 
the  light  during  the  intervals  that  /  remains  sta- 
tionary. The  synchronous  operation  of  the  inter- 
mittent sprocket  and  the  shutter  is  very  clearly 
shown  in  the  diagram.  A  lower  steady  feed  sprocket 
My  which  operates  at  the  same  speed  as  the  upper 
sprocket  E,  maintains  a  lower  feed  film  loop  N,  and 


114 


MOTION     PICTURE     PROJECTION 


ING      GEAR  WHEELS 

4  TO  I  REDUCTION 


MOTION    PICTURE     PROJECTION  115 

feeds  the  film  to  the  lower  reel  0.  Because  of  the 
increasing  diameter  of  the  roll  of  film  due  to  wind- 
ing the  film  on  reel  0,  the  velocity  of  rotation  of  0 
must  be  allowed  to  vary;  this  is  accomplished  by 
means  of  the  belt  drive  P,  the  belt  permitting  slip- 
page below  the  maximum  speed.  It  should  be  care- 
fully noted  that  the  total  revolutions  made  by  each 
of  the  three  sprockets  E,  I,  and  M,  is  the  same,  the 
only  difference  being  that  the  motion  of  E  and  M  is 
constant  while  that  of  I  is  intermittent. 


116  MOTION     PICTURE     PROJECTION 


Books  by  the  Same  Author 


Pocket   Reference   Book   for 
Managers  and  Projectionists 

Price  One  Dollar 

Elementary    Text    Book    on 
Motion   Picture  Projection 

Price  Two  Dollars 

Electricity  for  Motion  Picture 
Operators 

Price  Two  Dollars 

Motion  Picture  Optics 
(In  Preparation) 


THEATRE  SUPPLY  Co, 

124    WEST    45TH    STREET 
NEW  YORK  CITY 


MOTION     PICTURE     PROJECTION  117 


LIGHT 

That  light  travels  with  a  speed,  which  is  much 
greater  than  the  speed  of  sound  is  shown  by  the  fact 
that  the  flash  of  a  distant  gun  is  always  seen  long 
before  the  sound  of  the  report  is  heard  and  that 
lightning  always  precedes  thunder. 

For  most  purposes  it  is  sufficiently  accurate  to 
take  the  velocity  of  light  as  186,000  miles  per  second. 

Light  always  travels  out  from  a  source  in  straight 
lines. 

Up  till  the  year  1800,  the  Corpuscular  theory  of 
light  was  the  one  most  generally  accepted,  that  light 
consists  of  streams  of  very  minute  particles,  or  cor- 
puscles projected  with  the  enormous  velocity  of  186,- 
000  miles  per  second  from  all  luminous  bodies.  The 
facts  of  straight  line  propagation  and  reflection  are 
exactly  as  we  should  expect  them  to  be  if  this  were 
the  nature  of  light. 

A  usual  hypothesis  which  was  first  completely  for- 
mulated by  the  great  Dutch  physicist — Huygens 
(1629-1695),  regarded  light  like  sound,  as  a  form  of 
wave  motion.  This  hypothesis  met  at  the  first  with 
two  very  serious  difficulties;  in  the  first  place  light, 
unlike  sound,  not  only  travels  with  perfect  readiness 
through  the  best  vacuum  which  can  be  obtained  with 
an  air  pump,  but  it  travels  without  any  apparent 
difficulty  through  the  great  interstellar  spaces  which 
are  probably  infinitely  better  vacua  than  can  be  ob- 
tained by  artificial  means.  If,  therefore,  light  is  a 
wave  motion,  it  must  be  a  wave  motion  of  some  me- 
dium which  fills  all  space  and  yet  which  does  not 


118  MOTION    PICTURE     PROJECTION 

hinder  the  motion  of  the  stars  and  planets.   Huygens 
assumed  such  a  medium  to  exist,  and  called  it  ether. 

The  second  difficulty  in  the  way  of  the  wave  theory 
of  light,  was  that  it  seemed  to  fail  to  account  for  the 
fact  of  straight  line  propagation.  Sound  waves, 
water  waves  and  all  other  forms  of  waves  with  which 
we  are  familiar  bend  readily  around  corners,  while 
light  apparently  does  not.  It  was  this  difficulty 
chiefly  which  led  many  of  the  famous  philosophers, 
including  the  great  Sir  Isaac  Newton,  to  reject  the 
wave  theory  and  to  support  the  projected  particle 
theory. 

Within  the  last  hundred  years,  however,  this  diffi- 
culty has  been  completely  removed  and  in  addition 
other  properties  of  light  have  been  discovered,  for 
which  the  wave  theory  offers  the  only  satisfactory 
explanation.  If  the  wave  theory  is  to  be  accepted,  we 
must  conceive  with  Huygens,  that  all  space  is  filled 
with  a  medium,  called  the  ether,  in  which  the  waves 
can  travel.  This  medium  cannot  be  like  any  of  the 
ordinary  forms  of  matter ;  for  if  any  of  these  forms 
existed  in  interplanetary  space,  the  planets  and  the 
other  heavenly  bodies  would  certainly  be  retarded  in 
their  motion.  As  a  matter  of  fact,  in  all  the  hun- 
dreds of  years  during  which  astronomers  have  been 
making  accurate  observation  of  the  motion  of  hea- 
venly bodies  no  such  retardation  has  ever  been  ob- 
served. The  medium  which  transmits  light  waves, 
must  therefore  have  a  density  which  is  infinitely 
smaller  even  in  comparison  with  that  of  our  lightest 
gases.  The  existence  of  such  a  medium  is  now  uni- 
versally assumed  by  physicists. 

Just  as  sound  waves  are  disturbances  set  up  in  the 


MOTION     PICTURE     PROJECTION 


119 


air  by  the  vibrations  of  bodies  of  ordinary  dimen- 
sions, so  light  waves  are  disturbances  set  up  in  the 
ether  probably  by  the  vibrations  of  the  minute  cor- 
puscles or  electrons,  of  which  the  atoms  of  ordinary 
matter  are  supposed  to  be  built  up.  Since  these  cor- 
puscles are  extremely  small  in  comparison  with  ordi- 
nary bodies  it  is  not  surprising  that  their  rates  of 
vibration  are  enormously  larger  than  the  vibration 
rates  of  tuning  forks,  or  other  bodies  which  send  out 
sound  waves.  Just  how  these  corpuscles  are  set  into 
vibration  and  in  just  what  manner  they  vibrate,  we 
cannot  say  as  yet  with  certainty,  but  since  we  do 
know  that  an  increase  in  the  temperature  of  all 
bodies  means  an  increase  in  the  agitation  of  the  mole- 
cules and  atoms  of  which  these  bodies  are  composed. 
It  is  not  surprising  that  the  vibrations  which  com- 
municate light  waves  to  the  ether  take  place  in 
general  in  bodies  which  have  a  high  temperature  and 
that  the  hotter  the  body  becomes  the  more  intense 
becomes  the  light  waves  which  it  emits. 


i 


Snaplite  Lens 


120 


MOTION     PICTURE     PROJECTION 


PRINCIPLES  OF  OPTICAL  PROJECTION 

The  process  is  almost  the  reverse  of  ordinary 
photography.  For  instance,  in  photography  a  scene 
by  means  of  the  photographic  objective  or  lens  is 
photographed  and  a  reduced  image  is  obtained  on 
ground  glass.  This  glass  is  replaced  by  a  sensitized 
plate  and  by  the  use  of  chemicals  the  image  is  fixed 
thereon. 

In  projection  the  process  is  reversed,  that  is,  a 
transparent  slide  is  made  from  the  picture,  or  the 
roll  of  film  taken  with  the  motion  picture  camera  is 
developed  and  used  in  the  motion  picture  machine 
(the  projector).  By  means  of  a  condensed  light 
they  are  strongly  illuminated  and  with  an  objective 
lens  an  enlarged  image  is  projected  upon  the  screen, 
this  screen  image  corresponding  to  the  real  objects 
photographed.  The  principles  of  optical  projection 
for  motion  picture  machine  will  readily  be  understood 
from  the  diagram  below. 


Showing  the  Optical  System  of  a  Moving  Picture  Circuit  and 
How  Kays  of  Light  Travel  from  Arc  E  to  Screen  S 


MOTION     PICTURE     PROJECTION  121 

At  E  is  an  electric  arc  or  other  suitable  illuminant, 
the  light  from  which  is  caught  up  by  the  condenser  C. 
This  condenser  is  an  arrangement  of  lenses  so  con- 
structed as  to  gather  up  the  greatest  volume  of  light 
possible  and  to  concentrate  the  light  which  it 
gathers  at  the  center  or  diaphragm  plane  of  the 
objective  when  the  objective  is  located  at  the  proper 
distance  from  the  film,  which  distance  is  determined 
by  the  focal  length  of  objective  lens. 

The  film  should  be  placed  at  such  a  point  that 
the  entire  area  of  the  aperture  in  gate  is  fully  illu- 
minated, and  it  should  also  be  placed  so  that  the 
greatest  number  of  light  rays  possible  should  pass 
through  it. 

Proceeding  from  the  slide  D  or  film  F  the  light 
passes  through  the  objective  0,  where  the  rays  cross, 
and  the  object  is  therefore  reversed,  by  means  of  the 
objective,  the  object  is  also  imaged  or  delineated 
upon  the  screen  S,  the  degree  of  sharpness  or  flatness 
of  the  image  depends  upon  the  optical  connection  of 
the  lens. 

Great  care  should  be  taken  to  line  up  properly  the 
arc,  condensers  and  the  objective  lens,  as  under  the 
best  of  conditions  less  than  5%  of  the  light  from  arc 
reaches  the  screen. 


122  MOTION     PICTURE     PROJECTION 


LENSES 

The  optical  system  of  a  moving  picture  circuit 
comprises : 

(a)   The  arc  lamp  or  mazda  lamp. 

(6)   The  condensers. 

(c)   The  lens,  or  objective. 

The  optical  system  is  a  very  important  one  and 
one  that  has  long  been  neglected  by  the  majority  of 
operators.  A  number  of  men  who  have  been  operat- 
ing machines  for  years  have  never  taken  the  lenses 
apart  and  have  no  idea  of  the  different  combinations 
making  up  the  objective  lens. 

There  is  no  motion  picture  book  published  that  we 
know  of  which  goes  far  enough  into  this  matter,  and 
we  would  advise  anyone  desirous  of  getting  all  the 
information  possible  on  lenses  to  study  the  books 
dealing  with  this  subject  that  may  be  found  in  the 
various  libraries. 

The  following  is  an  outline  of  what  an  operator 
should  know,  and  has  been  gathered  from  several 
books  dealing  with  optical  systems  and  lenses. 

Reflection.  The  change  of  direction  experienced 
by  a  ray  of  light  when  it  strikes  a  surface  and  is 
thrown  back  or  reflected.  Light  is  reflected  accord- 
ing to  two  laws : 

(a)   The  angle  of  reflection  is  equal  to  the  angle 

of  incidence. 
(6)   The  incident  and  the  reflected  rays  are  both 

in  the  same  plane  which  is  perpendicular  to 

the  reflecting  surface. 


MOTION     PICTURE     PROJECTION  123 

Refraction.  The  change  of  direction  which  a  ray 
of  light  undergoes  upon  entering  obliquely  .a  medium 
of  different  density  from  that  through  which  it  has 
been  passing.  In  this  case  the  following  laws  obtain : 

(a)  Light  is  refracted  whenever  it  passes 
obliquely  from  one  medium  to  another  of 
different  optical  density. 

(6)  The  index  of  refraction  for  a  given  sub- 
stance is  a  constant  quantity  whatever  be 
the  angle  of  incidence. 

(c)  The  refracted  ray  lies  in  the  plane  of  the 
incident  ray  and  the  normal. 

(d)  Light   rays    are  .bent   toward   the   normal 
when  they  enter  a  more  refracted  medium 
and  from  the  normal  when  they  enter  a  less 
refracted  medium. 

A  lense  may  be  defined  as  a  piece  of  glass  or  other 
transparent  substance  with  one  or  both  sides  curved. 
Both  sides  may  be  curved,  or  one  curved  and  the 
other  flat. 

The  object  of  the  lens  is  to  change  the  direction  of 
rays  of  light  and  thus  magnify  objects  or  otherwise 
modify  vision. 

Lenses  may  be  classed  as : 

Double  convex  Double  concave 

Piano  convex  Piano  concave 

Concavo  convex  Convexo  concave 

The  focus  of  a  lens  is  the  point  where  the  refracted 
rays  meet. 

Spherical  Aberration.  The  reflected  rays  of  con- 
cave spherical  mirrors  do  not  meet  exactly  the  same 
point.  This  is  called  spherical  aberration. 


124  MOTION    PICTURE     PROJECTION 

Effect  of  Spherical  Aberration.  It  produces  a 
lack  of  sharpness  and  definition  of  an  image.  If  a 
ground  glass  screen  be  placed  exactly  in  the  focus 
of  a  lens  the  image  of  an  object  will  be  sharply  de- 
fined in  the  center  but  indistinct  at  the  edges,  and  if 
sharp  at  the  edges  it  will  be  indistinct  at  the  center. 
To  avoid  this  a  disc  with  a  hole  in  the  center  is  placed 
concentric  with  the  principal  axis  of  the  lens,  thus 
only  the  center  part  of  the  lens  is  used. 

Chromatic  Aberration.  When  white  light  is  passed 
through  a  spherical  lens,  both  refraction  and  disper- 
sion (the  decomposition  of  white  light  into  several 
kinds  of  light)  occur.  This  causes  a  separation  of 
the  white  light  into  the  various  colors  and  causes 
images  to  have  colored  edges.  This  effect  which  is 
most  observable  in  condenser  lenses  is  due  to  the  un- 
equal refrangibility  of  the  simple  colors. 

Achromatic  Lenses.  The  color  effect  caused  by 
the  chromatic  aberration  of  a  simple  lens  greatly  im- 
pairs its  usefulness.  This  may  be  overcome  by  com- 
bining into  one  lens,  a  convex  lens  of  crown  glass 
and  a  concave  lens  of  flint  glass. 

Back  Focal  Length.  The  distance  from  the  back 
of  the  lens  to  the  film  in  the  gate  of  machine  while  the 
film  is  in  focus  on  the  screen.  (Written  B.  F.) 

Equivalent  Focus.  The  distance  from  a  point  half 
way  between  the  back  and  front  combination  of 
lenses  to  the  film  in  the  gate  while  picture  is  in  focus 
on  screen. 

Can  be  obtained  by  measuring  the  distance  between 
the  front  and  back  combination  then  dividing  by 
two  and  adding  the  result  to  the  back  focal  length. 
(  Written  E.  F.) 


MOTION     PICTURE     PROJECTION 


125 


Objective  Lens.  The  objective  lens  of  a  moving 
picture  machine  generally  consists  of  four  lenses,  two 
in  the  front  combination  and  two  in  the  rear.  The 
two  lenses  in  the  front  are  cemented  together  with 
Canada  Balsam  and  called  the  compound  lens.  The 
back  combination  consists  of  two  lenses  separated  by 
a  metal  ring,  called  the  duplex  lens. 

The  convex  or  greatest  convex  side  of  a  lens  al- 
ways faces  the  screen. 

It  is  absolutely  necessary  to  keep  the  lenses  clean, 
it  will  be  impossible  to  get  good  definition  or  sharp 
focus  on  the  screen  if  the  objective  lens  is  not  scrupu- 
lously clean.  Never  place  the  fingers  on  the  glass 


Fig.l  Fig.2 


Fig.4 


Figures  1  and  2  the  crater  of  arc  needs  adjusting  laterally 

to  right  or  left 

Figures  3  and  4  the  crater  too  high  or  too  low 
Figures  5,  6  and  7  the  crater  is  too  near  or  too  far  away 

from  condenser 
Figure  8  shows  arc  in  correct  position 


126  MOTION     PICTURE     PROJECTION 

surface  of  lens,  as  though  it  may  not  show  when 
looking  through  the  lens  it  will  undoubtedly  affect 
the  definition  of  picture  on  screen. 

Condenser  lenses  should  be  cleaned  every  day,  and 
the  objective  lens  once  or  twice  a  week.  It  will  not 
be  found  necessary  to  take  the  lens  apart  to  do  this, 
as  it  will  only  be  the  exposed  glass  surfaces  that  will 
need  attention.  Use  a  clean  soft  handkerchief  for 
this  purpose.  The  lens  can  be  taken  apart  every 
three  or  four  months  and  all  surfaces  thoroughly 
cleaned,  great  care  should  be  taken  when  taking  the 
lens  apart  so  that  you  get  the  lenses  back  in  the 
same  position  and  order. 

Successful  results  in  projection  depend  largely 
upon  the  correct  adjustment  of  the  lamp,  which  must 
throw  a  brilliantly  illuminated  clear  circle  on  the 
screen.  After  the  objective  is  focused  as  will  be 
evidenced  by  a  sharp,  clear  image  on  the  creen, 
examine  the  illuminated  circle.  If  the  light  be  cen- 
tered and  the  lamp  correctly  adjusted,  the  circle 
will  be  entirely  free  from  coloration  or  shadows.  In 
Figures  1  and  2  the  crater  of  arc  needs  to  be  proper- 
ly adjusted  laterally,  it  being  as  shown  too  far  to 
the  right  or  left.  Figures  3  and  4  show  the  crater 
too  high  or  too  low.  In  Figures  5,  6  and  7  the  crater 
is  too  near  or  too  far  away  from  condensers.  Figure 
8  shows  it  in  right  position,  the  screen  being  free 
from  all  shadows  or  ghosts. 

Fig.  9  shows  the  various  lenses:  (a)  double  convex; 
(6)  piano  convex;  (c)  concavo  convex;  (d)  double 
concave;  (e)  piano  concave;  (/)  convexo  concave. 


MOTION     PICTURE     PROJECTION 


127 


The  first  three  are  thicker  at  the  center  than  at 
the  border,  and  are  called  converging;  the  second 
three  which  are  thinner  at  the  center  are  called  di- 
verging. 


B 


Fig.  9 


The  Gundlach-Manhattan  Optical  Co.,  makers  of 
the  Gundlach  Projection  Lens,  issue  the  following 
data  regarding  Lenses. 

The  Manufacture  of  lenses  presents  many  difficult 
problems  for  the  optician  to  contend  with  because  of 
the  peculiar  characteristics  of  optical  glass  as  well  as 
the  fact  that  it  is  not  a  material  easily  worked  owing 
to  its  hard,  brittle  nature.  To  produce  lenses  that 
are  well  corrected  in  the  optical  sense  and  maintain 
a  uniform  standard  of'  quality  requires  not  only 
scientific  knowledge  of  optics  and  mathematics  of  a 
high  order  to  compute  the  formula  but  also  the  ut- 
most skill  and  precision  must  be  used  during  the 
mechanical  operations  to  obtain  the  desired  result. 
Even  then  it  depends  upon  a  master  optician  for  the 
final  adjusting  and  testing  before  the  lens  is  ready 
for  market  because  a  good  lens  may  be  spoiled  by 
improper  mounting.  In  this  respect  lenses  are  dif- 
ferent from  articles  made  of  other  materials  which 


128  MOTION     PICTURE     PROJECTION 

can  readily  be  made  to  conform  to  dies,  patterns  or 
blue-print  specifications  with  certainty  that  when 
these  are  followed,  the  finished  article  will  be  perfect. 

Each  lens  goes  through  several  operations  of 
grinding  and  polishing  and  a  stray  bit  of  grit  may 
scratch  a  finished  surface  at  the  last  moment,  or 
lenses  will  crack  or  chip  in  handling,  adding  spoilage 
to  the  cost  of  manufacture. 

A  Projection  Lens  contains  three  distinct  kinds  of 
glass,  each  lot  of  glass  has  slightly  different  proper- 
ties and  as  one  melt  never  includes  more  than  a  few 
hundred  pounds  this  necessitates  a  constant  modifi- 
cation of  formulae  with  a  corresponding  changing 
of  tools  which  involves  a  big  expense. 

All  this,  of  course,  applies  to  a  maintainance  of  a 
standard  of  quality  and  explains  why  ordinary  pro- 
jection lenses  made  with  no  special  care  and  taken  as 
they  come  naturally  cost  a  great  deal  less  than 
Gundlach  Projection  Lenses  which  must  all  pass  the 
same  tests  and  reach  a  fixed  standard  of  quality  be- 
fore leaving  the  factory.  Further,  lenses  of  large 
aperture  require  more  care  in  grinding  and  polishing 
than  lenses  of  less  curvature  and  their  adjustment  is 
more  sensitive.  Besides,  the  larger  lenses  must  be 
made  separately  while  those  of  smaller  diameter  with 
flatter  surfaces  can  be  made  two  or  more  at  a  time 
reducing  the  cost  of  manufacture  proportionately. 

It  is  an  axiom  of  optics  that  the  best  lens  is  never 
too  good  for  the  purpose  and  this  is  particularly  true 
as  regards  projection,  it  being  obvious  that  a  poor 
lens  makes  a  picture  which  is  unsatisfactory  to  a 
large  number  of  people  and  the  theatre  owner  or 
producer  suffers  in  consequence  by  criticism  of  the 


MOTION     PICTURE     PROJECTION  129 

show  and  loss  of  business.  Now,  a  poor  lens  not  only 
will  not  focus  sharply  but  the  image  is  flattened  and 
lacks  contrast  because  what  should  be  black  becomes 
gray  and  light  and  shade  gradations  of  the  film  im- 
age are  not  reproduced  in  their  proper  values. 

Gundlach  Projection  Lenses  on  the  contrary  give 
uniformly  sharp  definition  with  the  utmost  illumina- 
tion and  the  picture  is  brilliant  because  all  the  con- 
trast of  the  film  is  preserved  while  the  shadows  show 
more  detail  due  to  the  additional  light  obtained  by 
their  large  working  aperture. 

The  Screen  Picture 

The  size  of  the  film  image  is  24x1"  and  the  opening 
in  the  aperture  plate  has  been  standardized  by  the 
principal  machine  manufactures  at  our  suggestion 
and  is  now  29/32"  wide  with  the  height  *A  of  the 
width.  The  picture  is  magnified  in  the  same  propor- 
tions, therefore,  the  screen  must  be  9  inches  high  for 
each  foot  in  width.  For  example,  9'xl2',  10'6"xl4" 
or  12'xl6'.  A  picture  16  ft.  wide  requires  a  magnifi- 
cation of  the  film  image  of  about  212  diameters  or 
nearly  44,944  times  the  size  of  the  original. 

The  importance  of  standardization  of  the  opening 
in  the  aperture  plate  may  be  realized  from  the  fact 
that  the  two  sizes  formerly  used  15/16!'  wide  and 
29/32"  wide  with  a  difference  of  only  1/32"  would 
result  in  a  difference  of  about  6  inches  between  the 
width  of  pictures  made  with  matched  lenses  for  a 
picture  16  ft.  wide  so  that  pictures  of  the  same  size 
could  be  obtained  only  by  using  lenses  of  different 
focal  lengths,  an  inconvenient  and  difficult  method  of 
securing  this  result. 


130  MOTION     PICTURE     PROJECTION 

It  is  our  opinion  that  the  quality  of  the  picture  is 
more  important  than  its  size,  or,  in  other  words,  we 
must  have  perfect  projection  as  the  first  consider- 
ation. Owing  to  the  unavoidable  loss  in  definition 
and  illumination  incidental  to  an  increase  in  magnifi- 
cation it  is  advisable  to  keep  the  size  of  the  picture 
within  a  reasonable  limit  which  we  think  is  about 
12x16.  Above  this  size  the  surface  area  increases 
very  rapidly  with  each  additional  foot  in  width.  The 
distance  the  picture  is  projected  is  not  so  important 
unless  it  necessiates  the  use  of  lenses  of  abnormally 
short  or  long  focus. 

Theoretically,  there  is  a  loss  of  light  in  inverse 
ratio  to  the  square  of  the  distance,  but  in  practice 
a  picture  of  a  given  size  can  be  projected  within  a 
reasonable  distance  without  any  noticable  change  in 
luminosity.  Obviously  this  imposes  a  limitation  to 
the  size  of  theatres,  therefore  it  is  not  advisable  to 
make  a  theatre  so  large  that  good  projection  cannot 
be  secured.  The  best  results  are  obtained  with  lenses 
ranging  between  4"  and  7^"  focal  length  and  any 
deviation  from  these  is  not  advisable. 

The  picture  is  projected  from  the  same  film 
whether  it  is  thrown  25  ft.  or  150  ft.  while  an  en- 
largement of  the  picture  is  secured  only  by  magnifi- 
cation of  the  film  image  with  a  consequent  depreci- 
ation of  the  light  by  spreading  it  over  a  greater 
surface.  The  definition  is  impaired  as  the  natural 
result  of  magnifying  a  film  image  which  is  not  ab- 
solutely sharp  to  begin  with.  On  the  contrary,  a 
difference  in  the  distance  does  not  bring  these  factors 
into  consideration  although  other  difficulties  arise  if 
an  effort  is  made  to  produce  too  large  a  picture  with 


MOTION     PICTURE     PROJECTION  131 

a  very  short  focus  lens  or  a  comparatively  small  pic- 
ture with  a  relatively  long  focus  lens.  The  thing  to 
avoid  is  extreme  or  abnormal  conditions  because  the 
best  result  can  be  obtained  only  by  being  careful  that 
each  factor  having  an  influence  upon  the  quality  of 
the  picture  is  normal  and  efficient.  Most  important 
of  these  is  Gundlach  Projection  Lenses  which  insure 
uniform  definition  with  a  brilliant  image  and  the  ut- 
most luminosity.  We  differentiate  between  brilliancy 
of  the  image  and  the  working  aperture  of  the  lens  or 
the  amount  of  light  it  collects  and  transmits  because 
the  former  is  determined  by  its  color  correction  which 
if  good,  will  preserve  the  contrast  of  the  film  and  if 
poor,  will  flatten  the  image  while  luminosity  is  merely 
the  inevitable  result  of  making  the  diameter  large  in 
proportion  to  the  focal  length. 

Three  principal  factors  govern  the  illumination  of 
the  picture,  first  the  light  source  including  its  ad- 
justment, current  consumption  and  condenser  system 
by  which  the  film  is  illuminated. 

Next  is  the  working  aperture  of  the  projection  lens 
or  the  ratio  between  its  diameter  and  focal  length. 

The  third  is  the  size  of  the  picture  or  its  surface 
area. 

The  working  aperture  of  the  lens  is  the  only  one 
in  which  we  are  directly  interested. 

This  ratio  in  Gundlach  Projection  Lenses  is  car- 
ried out  to  the  highest  degree  with  resulting  aper- 
tures of  F.2.  to  F.3.5.  according  to  the  focal  length 
is  not  being  practical  for  many  reasons  to  maintain 
a  uniform  aperture  of  F.2. 

That  the  size  of  the  picture  is  an  important  con- 
sideration is  evident  as  it  must  be  clear  that  the 


132  MOTION     PICTURE     PROJECTION 

same  amount  of  light  spread  over  a  larger  surface 
will  be  weaker. 

For  comparison  we  give  the  following  examples: 

Size  of  Picture  Surface  Area  Magnification 

9x12  108  sq.  ft.  158.88  diameters 

12x16  192  sq.  ft.  211.84  diameters 

15x20  300  sq.  ft.  264.80  diameters 

The  Projection  Lens 

This  we  have  already  mentioned  as  being  the  ratio 
between  the  diameter  and  focal  length  and  this  deter- 
mines the  amount  of  light  transmitted  by  lenses  of 
all  kinds.  Obviously  there  must  be  a  physical  limi- 
tation to  this  and  in  practical  optics  this  is  1 — 2,  so 
the  diameter  cannot  be  more  than  half  the  focal 
length.  Even  to  attain  this  result  is  an  achievement, 
it  involves  making  lenses  with  strong  curves,  each 
made  separately  with  the  utmost  care  and  great  pre- 
cision in  mounting  and  the  adjustment  of  the  com- 
ponents of  the  complete  lens  in  relation  to  each  other. 

This  means  the  distance  from  the  optical  center 
of  the  lens  to  the  point  where  it  defines  a  sharp  image 
when  focused  for  infinity  and  this  measurement  can 
be  made  accurately  only  by  optical  means.  Com- 
mercially we  grade  the  focal  lengths  in  quarter  inches 
in  engraving  the  cells  but  we  mark  the  exact  focal 
length  in  hundredths  of  an  inch  on  the  wrapper  and 
use  this  measurement  in  filling  orders. 

To  cite  an  instance  a  16  ft.  picture  at  99  ft.  re- 
quires a  lens  of  5.60  focus.  A  lens  of  exactly  5^2 
inch  (5.50)  focus  would  make  the  picture  oversize 
and  534  focus  would  be  too  long.  To  meet  this  con- 


MOTION     PICTURE     PROJECTION  183 


dition,  we  would  make  a  selection  from  5%"  lenses 
in  stock  of  those  the  nearest  to  5.60"  focus  but  longer 
rather  than  shorter.  .  Of  course  there  is  a  possibility 
in  every  case  that  an  error  in  measuring  the  distance 
will  be  a  disturbing  factor  and  some  allowance  should 
be  made  by  the  customer  for  some  difference  between 
the  size  of  the  picture  and  screen  which  is  unavoidable 
and  easily  painted  out. 

Lenses  are  matched  by  selection  as  the  focal  length 
cannot  be  modified  after  they  are  finished.  In  manu- 
facturing they  deviate  to  some  extent  from  the  focal 
length  prescribed  by  the  optical  formula  running 
both  under  and  over  for  which  reason  they  are  not 
necessarily  the  exact  focal  length  engraved  upon  the 
mounts.  For  example,  a  4"  lens  may  vary  within  the 
quarter  inch  from  3.95"  to  4.20",  it  being  our  practice 
to  mark  the  mounts  within  5/100"  under  to  20/100" 
over  of  the  actual  focal  length  and  it  will  be  per- 
ceived that  two  lenses  marked  with  the  same  focal 
length  may  at  the  most  have  a  difference  of  %"  and 
matching  for  pictures  of  the  same  size  necessitates 
that  both  lenses  shall  be  exactly  the  same  focal 
length.  This  being  the  case  the  lenses  must  be  match- 
ed when  they  leave  our  factory  unless  a  lens  to  be 
duplicated  is  sent  to  us  so  we  can  measure  it  or  if 
it  was  purchased  from  us  we  will  have  a  record  of 
its  focal  length  which  we  can  locate  if  given  the  order 
number  or  date  of  invoice.  The  exact  focus  in  hun- 
dredths  of  an  inch  is  shown  by  our  invoices  in  par- 
enthesis, for  example,  (4.36),  and  purchasers  should 
make  a  note  of  this  to  faciliate  placing  repeat  orders 
for  duplicates  when  they  wish  to  match  a  lens  or 
replace  one  which  has  been  damaged. 


134  MOTION    PICTURE     PROJECTION 

This  system  has  proven  a  great  convenience  to 
many  of  our  customers  and  constitutes  a  real  service 
which  adds  greatly  to  our  detail  in  making  and  sup- 
plying lenses.  Sometimes  we  are  called  upon  to 
match  or  duplicate  a  lens  we  sold  several  months  or 
years  ago,  and  it  is  quite  an  advantage  to  the  custom- 
er to  get  a  new  lens  that  will  make  the  picture  the 
same  size  it  was  before  without  any  loss  of  time. 

It  should  be  noted  by  every  user  of  a  projection 
lens  that  the  components  are  not  interchangeable  and 
no  liberty  whatever  should  be  taken  with  the  arrange- 
ment or  adjustment  of  a  lens.  A  broken  element  can- 
not be  replaced  unless  the  complete  lens  is  returned 
for  repairs  and  the  broken  parts  should  be  preserved 
as  they  may  be  useful  in  determining  the  exact  origin- 
al focal  length,  otherwise  this  may  be  changed  by 
replacing  the  broken  lens.  Odd  combinations  or  lens- 
es are  absolutely  of  no  value  and  we  cannot  under- 
take to  utilize  them  to  make  up  complete  lenses  or 
for  repairs. 

The  condition  of  many  lenses  sent  in  to  us  in- 
dicates great  carelessness  in  handling  them  and  Pro- 
jectionists should  be  cautioned  to  handle  them  more 
gently.  There  is  positively  no  excuse  for  so  many 
scratched  surfaces,  broken  lenses  and  ruined  mounts 
after  allowing  for  reasonable  accidents. 

The  terms  quarter  and  half  size  have  no  real  place 
in  optical  nomenclature  although  commonly  used. 
No  doubt  they  originated  in  the  early  days  of  photog- 
raphy when  applied  to  portrait  lenses  used  for  quart- 
er size  (3/4x4%)  and  half  size  (4)4x6^)  cameras. 
These  were  the  first  lenses  used  for  projection  and 
eventually  each  size  was  made  in  a  number  of  different 


MOTION     PICTURE     PROJECTION  135 

focal  lengths.  The  Projection  Lenses  of  to-day  are 
made  by  a  modification  of  the  formula  of  the  original 
Petzvel  Portrait  Lens  which  we  have  brought  to  per- 
fection with  the  improved  optical  glass  at  our  com- 
mand. The  sizes  of  Gundlach  Projection  Lenses  are 
numbered  to  prevent  them  from  being  unfairly  com- 
pared or  confused  with  so-called  quarter  and  half  size 
lenses  of  smaller  diameter  and  less  light  efficiency. 

We  wish  to  make  it  clear  that  there  is  no  optical 
difference  between  our  No.  1  and  No.  2  size  Projec- 
tion Lenses.  The  No.  2  size  is  merely  a  continuation 
of  the  No.  1  size,  providing  longer  focal  lengths  with 
the  same  relative  working  aperture  to  maintain  the 
illuminating  power  but  it  is  evident  that  in  cor- 
responding focal  lengths  the  No.  2  size  will  transmit 
more  light  than  the  smaller  size,  therefore,  it  is  a 
decided  advantage  to  use  the  No.  2  lenses  in  any 
focal  length  in  which  they  are  made  from  5^4"  up. 
If  the  increased  illumination  is  not  needed  on  the 
screen  it  can  be  saved  in  current  so  the  lens  of  large 
aperture  is  an  economy  to  this  extent. 

To  answer  a  question  frequently  put  to  us,  we 
state  that  the  keystone  effect  incidental  to  projecting 
the  picture  from  an  angle  can  not  be  corrected  by 
the  Projection  Lens,  this  being  the  natural  result 
of  a  difference  in  the  length  of  the  light  rays  from 
the  lens  to  the  top  and  bottom  or  sides  of  the  screen 
as  the  case  may  be,  causing  a  greater  magnification 
of  the  image  at  one  point  than  at  the  other.  Theatre 
architects  should  be  informed  that  the  location  of 
the  operating  room  should  be  planned  to  bring  the 
machines  in  a  horizontal  line  with  the  center  of  the 
screen. 


136  MOTION     PICTURE     PROJECTION 

In  event  that  lenses  we  supply  do  not  make  the 
picture  close  enough  to  the  desired  size,  on  account  of 
an  error  in  measuring  the  distance,  report  at  once 
the  exact  width  of  the  picture  they  produce  and  we 
can  then  allow  for  the  error  and  determine  what  the 
distance  actually  is  and  the  focal  length  required. 

If  you  want  Gundlach  lenses  to  make  a  picture  the 
same  size  as  it  is  made  by  some  other  lens  send  the 
lens  to  us  to  be  measured  because  you  cannot  depend 
upon  the  focal  length  engraved  on  the  mount. 

Computing  the  Focal  Length 

The  focal  length  required  is  ascertained  by  a 
computation  based  upon  the  size  of  the  opening  in 
the  aperture  plate,  the  size  of  the  picture  wanted 
and  the  distance  it  is  to  be  projected. 

The  distance  is  somewhat  uncertain  owing  to  er- 
rors made  in  measuring  it  which  we  have  known  to 
amount  to  as  much  as  fifteen  feet  but  in  case  a 
mistake  has  been  made  by  which  lenses  of  the  wrong 
focus  have  been  secured  it  is  easily  rectified.  We 
should  then  be  informed  the  exact  width  of  the  picture 
made  by  the  lenses  the  customer  has  received  and  as 
we  have  a  record  of  their  exact  focus,  we  can  calcu- 
late from  these  two  factors  what  the  correct  distance 
is  and  determine  the  proper  focal  length  of  the  lenses 
to  send  in  exchange.  The  distance  of  projection  can 
be  obtained  by  referring  to  the  architect's  plans  of 
the  theatre  if  these  are  available. 

Measure  the  distance  accurately,  and  you  can  de- 
pend upon  us  to  supply  lenses  of  the  correct  focal 
length. 


MOTION    PICTURE     PROJECTION  187 

Cleaning  and  Assembling 

First  note  whether  the  extension  tube  is  attached 
to  the  front  or  rear  end  so  you  will  replace  it  cor- 
rectly. Clean  both  sides  of  the  front  combination  but 
do  not  remove  it  from  the  cell.  To  remove  the  re- 
taining ring  from  the  rear  cell,  press  lightly  on  op- 
posite sides  of  the  ring  with  two  fingers  and  unscrew 
it.  Too  much  pressure  will  make  it  bind  so  it  will 
not  turn.  Clean  inside  surfaces  of  the  two  lenses  of 
the  rear  combination  and  replace  in  the  cell.  Be 
careful  they  are  seated  evenly,  then  screw  up  the 
retaining  ring  just  tight  enough  to  prevent  them 
from  moving,  then  clean  the  outside  surface. 

The  rear  lens  is  convex  on  both  sides  and  the  flatter 
side  is  the  outside  rear  surface.  The  retaining  rings 
should  face  towards  the  centre;  reversing  the  cells 
will  disturb  the  correction. 

To  remove  grease  or  oil  from  the  surface  of  the 
lens  use  a  soft  rag  free  from  grit,  moistened  with  a 
little  gasoline. 

Be  careful  when  screwing  the  parts  together  to 
avoid  skipping  a  thread  and  do  not  screw  up  any 
joints  very  tight. 

Do  not  use  a  hard  sharp  tool  to  remove  the  retain- 
ing rings  or  it  may  slip  and  scratch  the  lenses. 


138 


MOTION     PICTURE     PROJECTION 


LENS  TABLE  OF  FILM  PROJECTION 

DISTANCE  FROM  FILM   TO  SCREEN 


Stero. 

M.P. 

15 

20 

25 

30     |      35 

40 

45 

8 

2 

5.04 

6.74 

8.44 

10.14 

11.84 

13.54 

15.24 

6.72 

8.99 

11.25 

13.52 

15.78 

18.05 

20.31 

9 

2J4 

4.48 

5.99 

7.50 

9.01 

10.52 

12.03 

13.54 

5.97 

7.98 

10.00 

12.01 

14.03 

16.04 

18.05 

10 

21A 

4.02 

5.38 

6.74 

8.10 

9.46 

10.82 

12.18 

5.36 

7.17 

8.99 

10.80 

12.61 

14.42 

16.24 

11 

2# 

3.65 

4.89 

6.12 

7.36 

8.59 

9.83 

11.06 

4.87 

6.52 

8.17 

9.18 

11.46 

13.11 

14.76 

12 

3 

3.34 

4.47 

5.61 

6.74 

7.87 

9.00 

10.14 

4.46 

5.97 

7.48 

8.99 

10.50 

12.01 

13.52 

13 

3J4 

3.08 

4.13 

5.17 

6.22 

7.26 

8.31 

9.35 

4.11 

5.50 

6.90 

8.19 

9.69 

11.08 

12.48 

14 

sy. 

2.86 

3.83 

4.80 

5.77 

6.74 

•    7.72 

8.69 

3.81 

5.10 

6.40 

7.69 

8.99 

10.28 

11.58 

15 

3*4 

2.66 

3.57 

4.47 

5.38 

6.28 

7.19 

8.10 

3.55 

4.76 

5.97 

7.17 

8.38 

9.59 

10.80 

16 

4 

2.49 

3.34 

4.19 

5.04 

5.98 

6.74 

7.59 

3.32 

4.45 

5.59 

6.72 

7.85 

8.98 

10.12 

17 

4# 

2.34 

3.14 

3.94 

4.74 

5.54 

6.34 

7.14 

3.12 

4.19 

5.25 

6.32 

7.38 

8.45 

9.52 

18 

4# 

2.21 

2.97 

3.72 

4.48 

5.23 

5.99 

6.74 

2.95 

3.96 

4.96 

5.97 

6.98 

7.98 

8.99 

19 

4*4 

2.09 

2.81 

3.52 

4.24 

4.95 

5.67 

6.38 

2.79 

3.74 

4.70 

5.65 

6.61 

7.56 

8.51 

20 

5 

1.98 

2.66 

3.34 

4.02 

4.70 

5.38 

6.06 

2.64 

3.55 

4.45 

5.36 

6.27 

7.17 

8.08 

21 

5*4 

1.89 

2.54 

3.18 

3.8* 

4.48 

5.13 

5.77 

2.51 

3.37 

4.24 

5.10 

5.96 

6.83 

7.69 

22 

5*4 

1.80 

2.42 

3.04 

3.65 

4.27 

4.89 

5.51 

2.40 

3.22 

4.05 

4.87 

5.70 

6.52 

7.34 

23 

6# 

1.72 

2.31 

2.90 

3.49 

4.08 

4.67 

5.27 

2.29 

3.08 

3.87 

4.65 

5.44 

6.23 

7.02 

24 

6 

1.64 

2.21 

2.77 

3.34 

3.91 

4.47 

5.04 

2.19 

2.95 

3.70 

4.46 

5.21 

5.97 

6.72 

25 

654 

1.57 

2.11 

2.66 

3.20 

3.75 

4.29 

4.83 

2.10 

2.82 

3.55 

4.27 

5.00 

5.72 

6.45 

26 

6# 

1.51 

2.03 

2.56 

3.08 

3.60 

4.12 

4.65 

2.02 

2.72 

3.41 

4.11 

4.81 

5.51 

6.20 

27 

634 

1.45 

1.95 

2.46 

2.96 

3.46 

3.97 

4.47 

1.94 

2.61 

3.28 

3.95 

4.63 

5.30 

5.97 

28 

7 

1.40 

1.89 

2.37 

2.86 

3.34 

3.83 

4.31 

1.87 

2.52 

3.16 

3.81 

4.46 

5.11 

5.75 

29 

7*4 

1.35 

1.82 

2.29 

2.76 

3.23 

3.69 

4.16 

1.80 

2.42 

3.05 

3.67 

4.30 

4.92 

5.69 

30 

7'/4 

1.30 

1.75 

2.21 

2.66 

3.11 

3.57 

4.02 

1.74 

2.34 

2.95 

3.55 

4.16 

4.76 

5.37 

81 

7*4 

1.26 

1.70 

2.14 

2.58 

3.01 

3.45 

3.89 

1.68 

2.26 

2.85 

3.43 

4.02 

4.60 

5.19 

82 

8 

1.22 

1.64 

2.07 

2.49 

2.92 

3.34 

3.77 

1.62 

2.19 

2.75 

3.32 

3.89 

4.45 

5.02 

83 

8J4 

1.18 

1.59 

2.00 

2.42 

2.83 

3.24 

3.65 

1.57 

2.12 

2.67 

3.22 

3.77 

4.32 

4.87 

34 

8*4 

1.14 

1.54 

1.94 

2.34 

2.74 

3.14 

3.54 

1.52 

2.05 

2.59 

3.12 

3.65 

4.19 

4.72 

85 

8*4 

1.11 

1.50 

1.88 

2.27 

2.66 

3.05 

3.43 

1.48 

2.00 

2.51 

3.03 

3.55 

4.06 

4.58 

MOTION     PICTURE     PROJECTION 


139 


LENS  TABLE  OF  FILM  PROJECTION— Continued 

DISTANCE   FROM    FILM    TO    SCREEN 


Stero. 

M.P. 

60 

56 

60 

64 

70 

76 

80 
1 

8 

2 

16.93 

18.97 

20.33 

21.69 

23.73 

25.77 

27.13 

22.58 

25.30 

27.11 

28.92 

31.64 

34.46 

36.17 

9 

254 

15.05  '  16.87 

18.07 

19.28 

21.09 

22.91 

24.12 

20.07 

22.48 

24.10 

25.71 

28.12 

30.54 

32.15 

10 

2y* 

13.54 

15.17 

16.26 

17.34 

18.98 

20.61 

21.70 

18.05 

20.22 

21.67 

23.12 

25.30 

27.47 

28.1)2 

11 

2# 

12.30 

13.78 

14.77 

15.76 

17.24 

18.73 

19.72 

16.40 

18.38 

19.70 

21.01 

22.99 

24.97 

26.2!) 

12 

3 

11.27 

12.63 

13.54 

14.44 

15.80 

17.16 

18.07 

15.03 

16.85 

18.05 

19.26 

21.07 

22.89 

24.10 

13 

354 

10.40 

11.65 

12.49 

13.33 

14.58 

15.84 

16.67 

13.87 

15.54 

16.66 

17.77 

19.45 

21.12 

22.23 

14 

354 

9.66 

10.82 

11.60 

12.38 

13.54 

14.71 

15.48 

12.87 

14.43 

15.46 

16.50 

18.05 

19.60 

20.64 

15 

sy4 

9.00 

10.09 

10.82 

11.54 

12.63 

13.72 

14.44 

12.00 

13.46 

14.42 

15.39 

16.84 

18.29 

19.26 

16 

4 

8.44 

9.46 

10.14 

10.82 

11.84 

12.86 

13.54 

11.25 

12.61 

13.52 

14.42 

15.78 

17.14 

18.05 

17 

454 

7.94 

8.90 

9.54 

10.1?  i  11.14 

12.10 

12.74 

10.58 

11.86 

12.72 

13.57     14.85 

16.13 

16.98 

18 

454 

7.50 

8.40 

9.01 

9.61     10.52 

11.42 

12.0:{ 

9.10 

11.21 

12.01 

12.82  1  14.03 

15.23 

16.04 

19 

4& 

7.10 

7.96 

8.53 

9.10       9.96 

10.82 

11.39 

9.47 

10.61 

11.38 

12.14     13.28 

14.43 

15.1!) 

20 

5 

6.74 

7.55 

8.10 

8.64       9.46 

10.27 

10.82 

8.98 

10.07 

10.80 

11.52     12.62 

13.70 

14.42 

21 

654 

6.42 

7.20 

7.72 

8.23       9.01 

9.79 

10.30 

8.55 

9.59 

10.28 

10.97     12.00 

13.04 

13.73 

22 

554 

6.13 

6.87  , 

7.36 

7.86       8.60 

9.34 

9.83 

8.17 

9.16 

9.82 

10.47     11.46 

12.45 

13.11 

23 

5*4 

5.86 

6.57 

7.04 

7.51       8.22 

8.93 

9.40 

7.81 

8.75 

9.38 

10.01     10.96 

11.90 

12.53 

24 

6 

5.60 

6.28 

6.74 

7.19       7.87 

8.55 

9.00 

7.48 

8.38 

8.99 

9.59     10.50 

11.40 

12.01 

25 

654 

5.38 

6.03 

6.46 

6.90       7.55 

8.20 

8.64 

7.17 

8.04 

8.62 

9.20     10.07 

10.94 

11.52 

26 

654 

5.17 

5.80 

6.22 

6.63       7.26 

7.89 

8.JH 

6.90 

7.74 

8.39  , 

8.85       9.69 

10.53 

11.08 

27 

6tf 

4.98 

5.58 

5.98 

6.38       6.99 

7.59 

8.00 

6.64 

7.44 

7.98 

8.52       9.32 

10.13 

10.67 

28 

7 

4.80 

5.38 

5.77 

6.16       6.74 

7.32 

7.71 

6.40 

7.18 

7.70 

8.21       8.99 

9.77 

10.28 

29 

7^4 

4.63 

5.19 

5.57 

5.94       6.51 

7.07 

7.44 

6.17 

6.92 

7.42 

7.92       8.67 

9.43 

9.!K{ 

30 

754 

4.47 

5.02 

5.38 

5.74       6.28 

6.83  , 

7.1!) 

5.97 

6.69 

7.18 

7.66       8.39 

9.11 

9.5!) 

31 

734 

4.33 

4.86 

5.21 

5.56       6.08 

6.61 

6.  SMI 

5.77 

6.48 

6.95 

7.42       8.12 

8.82 

9.2!) 

32 

8 

4.19 

4.70 

5.04 

5.38       5.89 

6.40 

6.74 

5.58 

6.26 

6.72 

7.17       7.85 

8.53 

8.98 

33 

854 

4.06 

4.56 

4.89 

5.22       5.71 

6.21 

6.54 

5.41 

6.07 

6.51 

6.95       7.61 

8.27 

8.7t 

34 

8}4 

4.42 

4.74 

5.06       5.54 

6.02  , 

6.34 

5  25 

5.89 

6.32  , 

6.74"       7.38 

8.02 

8.44 

35 

8*4 

3^82 

4.29 

4.60 

4.91       5.38 

5.84 

6.15 

5.10 

5.72 

6.13 

5.65       7.17 

7.79 

8.20 

140 


MOTION    PICTURE     PROJECTION 


LENS  TABLE  OF  FILM  PROJECTION— Continued 

DISTANCE  FROM  FILM   TO  SCREEN 


Stero. 

M.P. 

84 

90 

96 

100 

104 

110 

116 

8 

2 

28.49 

30.53 

32.57 

33.93 

35.29 

37.33 

39.36 

37.99 

40.71 

43.42 

45.24 

47.05 

49.77 

52.49 

9 

2J4 

25.32 

27.14 

28.95 

30.16 

31.37 

23.18 

34.99 

33.76 

36.18 

38.60 

40.21 

41.82 

44.24 

46.55 

10 

2X 

22.78 

24.42 

26.05 

27.14 

28.22 

29.86 

31.49 

30.37 

32.55 

34.72 

36.17 

37.62 

39.80 

41.97 

11 

2Y4 

20.70 

22.19 

23.67 

24.66 

25.65 

27.13 

28.61 

27.61 

29.59 

31.56 

32.88 

34.20 

36.18 

38.15 

12 

3 

18.97 

20.33 

21.69 

22.60 

23.50 

24.86 

26.22 

25.30 

27.12 

28.93 

30.14 

31.35 

33.16 

34.97 

13 

3J4 

17.51 

18.77 

20.02 

20.86 

21.69 

22.95 

24.20 

23.35 

25.02 

26.70 

27.81 

28.93 

30.60 

32.27 

14 

3J4 

16.26 

17.43 

18.59 

19.37 

20.14 

21.31 

22.47 

21.68 

23.23 

24.78 

25.82 

26.86 

28.41 

29.96 

15 

8# 

15.17 

16.25 

17.34 

18.07 

18.79 

19.88 

20.97 

20.22 

21.67 

23.12 

24.09 

25.06 

26.51 

27.96 

10 

4 

14.22 

15.24 

16.25 

16.93 

17.61 

18.63 

19.65 

18.95 

20.31 

21.67 

22.58 

23.48 

24.84 

26.20 

17 

4'4 

13.38 

14.34 

15.30 

15.94 

16.57 

16.52 

18.48 

17.83 

19.11 

20.39 

21.25 

22.10 

23.38 

24.66 

18 

4J4 

12.63 

13.54 

14.44 

15.05 

15.65 

16.56 

17.47 

16.85 

18.05 

19.26 

20.07 

20.87 

22.08 

23.29 

19   , 

4^ 

11.96 

12.82 

13.68 

14.25 

14.83 

15.86 

16.54 

15.96 

17.10 

18.24 

19.10 

19.77 

20.92 

22.06 

20 

6 

11.36 

12.28 

12.99 

13.54 

14.08 

14.89 

15.71 

15.15 

16.23 

17.32 

18.05 

18.77 

19.86 

20.95 

21 

5*4 

10.82 

11.60 

12.38 

12.89 

13.41 

14.19 

14.96 

14.42 

15.46 

16.49 

17.18 

17.87 

18.91 

19.94 

22 

6# 

10.33 

11.07 

11.81 

12.31 

12.80 

13.54 

14.28 

13.77 

14.76 

15.73 

16.40 

17.07 

18.06 

19.04 

23 

5H 

9.88 

10.59 

11.29 

11.77 

12.24 

12.95 

13.66 

13.16 

14.11 

15.06 

15.69 

16.32 

17.26 

18.21 

24 

6 

9.46 

10.14 

10.82 

11.27 

11.72 

12.40 

13.08 

12.61 

13.52 

14.42 

15.03 

15.63 

16.54 

17.45 

25 

654 

9.07 

9.73 

10.38 

10.81 

11.25 

11.90 

12.55 

2.10 

12.97 

13.84 

14.42 

15.00 

15.87 

16.74 

26 

&/, 

8.72 

9.35 

9.98 

10.40 

10.82 

11.44 

12.07 

11.64 

12.48 

13.31 

13.87 

14.43 

15.27 

16.10 

27 

6*4 

8.40 

9.00 

9.60 

10.01 

10.41 

11.02 

11.62 

11.20 

12.01 

12.81 

13.35 

13.89 

14.69 

15.50 

28    , 

7 

8.10 

8.68 

9.27 

9.65 

10.04 

10.62 

11.21 

10.80 

11.58 

12.36 

12.87 

13.39 

14.17 

14.94 

29 

7J4 

7.82 

8.38 

8.94 

9.32 

9.69 

10.26 

10.82 

10.42 

11.17 

11.93 

12.43 

12.93 

13.68 

14.43 

80 

7*4 

7.55 

8.10 

8.64 

9.00 

9.37 

9.91 

10.45 

10.08 

10.80 

11.53 

12.01 

12.50 

13.22 

13.95 

81 

7*4 

7.31 

7.84 

8.36 

8.71 

9.07 

9.59 

10.12 

9.76 

10.46 

11.16 

11.63 

12.10 

12.80 

13.50 

32 

8 

7.08 

7.59 

8.10 

8.44 

8.78 

9.29 

9.80 

9.44 

10.12 

10.80 

11.25 

11.70 

12.38 

13.06 

33 

854 

6.86 

7.36 

7.85 

8.18 

8.51 

9.01 

9.50 

9.15 

9.81 

10.47 

10.91 

11.35 

12.01 

12.66 

34 

8J4 

6.66 

7.14 

7.62 

7.94 

8.26 

8.74 

9.22 

8.88 

9.52 

10.16 

10.58 

11.01 

11.65 

12.29 

85 

8*4 

6.46 

6.93 

7.40 

7.71 

8.02 

8.48 

8.95 

8.62 

9.24 

9.86 

10.27 

10.6 

11.31 

11.93 

i 

1 

MOTION    PICTURE     PROJECTION  141 


THREE  COMBINATION  LENS 

There  is  now  on  the  market  a  three  combination 
lens,  known  as  the  Keen-o-lite  three  combination  lens ; 
it  is  so  constructed  that  the  rear  objective  lens  is 
never  more  than  two  inches  from  the  aperture  plate, 
thus  giving  an  increased  light  illumination  on  the 
screen,  after  allowing  for  the  additional  reflection 
and  absor'tion  loss  due  to  the  extra  third  combina- 
tion. Below  is  the  report  of  Professor  Weinrich  of 
Columbia  University  who  lately  made  some  compar- 
ative tests  with  the  lens. 

Report  of  Professor  Weinrich  of  Columbia  University. 

I  herewith  submit  report  oh  my  comparative  test  of  a 
KEEN-O-LITE  and  a  lens  of  another  make,  both  of  six  and 
three  quarters  inch -focal  length. 

The  primary  object  of  the  test  was  to  compare  the  illumina- 
tion produced  upon  the  screen  by  the  Keen-o-lite  Lens  and 
another  projection  lens  of  high  standing  and  the  same  focal 
length,  the  same  light  flux  passing  through  the  frame-plate  in 
both  cases. 

As  the  design  of  the  "Keen-o-lite"  lens  is  based  upon  the 
actual  conditions  as  they  exist  in  the  modern  projection  ma- 
chine it  may  be  well  to  first  consider  these  conditions  from  a 
somewhat  theoretical  point  of  view. 

The  most  practical  way  of  adjusting  the  arc,  condensers  and 
frame-plate  of  a  projection  machine  is  such  as  to  produce  an 
enlarged  image  of  the  positive  crater,  a  little  larger  than  the 
aperture,  upon  the  frame-plate.  In  order  that  the  picture  be 
as  uniformly  illuminated  and  spotless  as  possible,  Jt  is  best  to 
have  the  most  concentrated  part  of  the  beam  and  the  sharpest 
image  of  the  crater  a  short  distance  from  the  frame-plate,  on 
the  condenser  side;  i.  e.,  have  a  slightly  extra  focal  image 
thrown  upon  the  aperture.  This  adjustment  naturally  pro- 
duces a  diverging  beam  through  the  aperture  of  the  frame- 
plate.  In  order  to  utilize  as  much  as  possible  of  this  diverging 
beam  we  either  have  to  allow  the  light  to  fall  upon  a  compara- 
tively small  lens  placed  near  the  aperture  or  a  comparatively 
large  one  a"  greater  distance  away.  In  the  design  of  the  Keen- 


142  MOTION     PICTURE     PROJECTION 


o-lite  lens  the  former  of  these  two  methods  was  adopted  and 
skilfully  executed.  The  "back  focus"  of  the  ordinary  type  of 
6% -inch  lens  is  about  6  inches  while  in  the  case  of  the  Keen- 
o-lite  it  is  only  a  little  more  than  one-third  as  much,  and  the 
clear  aperture  of  the  back  lens  is  only  slightly  smaller  than 
that  of  the  other.  The  entering  beam  in  the  case  of  the  "Keen- 
o-lite"  is  therefore  very  considerably  larger,  and  with  it  the 
total  brightness  of  the  picture  as  was  verified  by  test. 

There  are,  however,  two  further  advantages  of  the  Keen-o- 
Hte  lens  which  are  even  more  important  than  the  foregoing. 
They  are:  a  more  uniformly  illuminated  picture,  from  center  to 
edge  or  corner,  and  better  definition. 

The  rays  which  the  ordinary  lens  does  not  utilize  are  to  a 
much  greater  exTent  from  the  edges  and  corners  of  the  film 
than  from  the  central  part  and  therefore  would  increase  the 
illumination  of  these  parts  of  the  picture  relatively  to  the 
center,  thereby  producing  a  more  uniform  illumination  over 
the  entire  surface  of  the  screen. 

The  definition  given  by  a  lens  can  in  general  be  made  more 
perfect  by  the  addition  of  more  elements  and  curved  surfaces. 
The  addition  of  the  extra  element  of  the  Keen-o-lite  has  pro- 
duced a  lens  of  very  decidedly  better  definition  than  any  other. 

The  figures  hereinafter  given  were  obtained  with  a  set-up 
like  that  of  the  average  machines  using  6^ -in.,  7^-in.  con- 
densers. The  source  was  brightly  illuminated  opal  glass 
bounded  by  a  ^-in.  circular  aperture  in  imitation  of  the  posi- 
tive crater.  The  position  of  source  condensers  and  frame- 
plate  were  absolutely  the  same  during  all  tests  and  the  bright- 
ness of  the  source  invariable.  The  conditions  were  hence  the 
same  as  in  the  projection  machine  itself  but  their  invariability 
made  the  test  much  more  dependable  than  if  an  arc  had  been 
used.  The  results  of  the  test  were  as  follows: 

Keen-o-lite  gave  12.5%  more  light  at  center  of  screen. 
Keen-o-lite  gave  82.5%  more  light  half  way  out  to  corner. 
Keen-o-lite  gave  63.0%  more  light  at  corners. 

Integrating  these  results  we  find  that  the  total  illumination 
of  the  screen  is  about  32.8%  greater  in  the  case  of  the  Keen- 
o-lite  lens  over  the  lens  of  another  make. 

The  definition  given  by  the  Keen-o-lite '  is  also  decidedly 
superior. 


MOTION     PICTURE    PROJECTION  148 


ROBIN  CINEMA  ELECTRIC  TIME   SYSTEM 

This  system,  invented  by  J.  E.  Robin  in  1914,  is 
what  the  name  implies,  a  system  to  provide  an  ac- 
curate and  predetermined  running  schedule  for  mo- 
tion picture  and  synchronizing  the  music  with  same. 

It  is  an  electrical  speed  indicating  device,  con- 
sisting of  a  small  extremely  accurate  direct  current 
generator  attached  to  the  projection  machines  and 
connected  to  a  very  sensitive  meter  by  cable.  The 
meter  is  calibrated  with  the  generator  and  shows  in 
feet  per  minute  and  the  rate  of  time  per  thousand 
feet  at  which  the  film  is  being  operated.  In  operation 
the  voltage  generated  varies  with  the  speed  of  the 
machine  causing  a  corresponding  increase  or  decrease 
of  the  connected  meters. 

Plate  No.  1  shows  a  single  unit  consisting  of  a 
generator,  meter  and  cable  for  a  single  machine. 

PLATE  1 


Generator  and  Meter,  Single  Unit 


144 


MOTION    PICTURE     PROJECTION 


PLATE  4 


Robin  Speed  Indicator  Attached  to  Simplex  Projector 


MOTION     PICTURE     PROJECTION  14-5 

Plate  No.  2  shows  an  equipment  for  two  projection 
machines  with  switchboard  and  two  meters. 

PLATE  2 


Robin  Indicator  for  Two  Machines  with  Two  Indicators 

Plate  No.   4  shows   Robin  speed  indicators  with 
switchboard  as  attached  to  a  Simplex  machine. 


146 


MOTION     PICTURE     PROJECTION 


Plate  No.  3  as  attached  to  Powers  projector. 
PLATE  3 


Robin  Speed  Indicator  Attached  on  Powers  Machine 


MOTION     PICTURE     PROJECTION 


147 


The  meters  and  generators  are  made  of  the  best 
materials  throughout  and  are  carefully  tested  prior 
to  leaving  the  factory  and  the  operator  should  ex- 
perience no  trouble  whatsoever  in  maintaining  the 


same. 


The  generators  are  ballbearing  and  contain  suf- 
ficient grease  to  last  for  a  year  and  therefore  re- 
quire practically  no  attention  whatsoever. 

In  ordering  speed  indicators  it  is  necessary  to 
specify  the  make  and  type  of  the  projection  ma- 


Robin  Signal  Telegraph  With  Eight  Synchronized  Meters  as 
Installed  in  New  York  Capitol 


148  MOTION     PICTURE     PROJECTION 

chines,  the  diameter  of  the  shutter  shaft  and  the  dis- 
tance for  the  cable  required.  Where  it  is  desired  to 
use  a  meter  in  the  orchestra  pit,  the  distance  be- 
tween the  two  projection  machines  and  the  orchestra 
pit,  measured  on  one  side  of  the  circuit,  should  be 
given. 

In  the  majority  of  the  larger  theatres  it  is  custom- 
ary for  the  director  to  be  present  in  the  reviewing 
room  at  the  time  the  rehearsal  is  made.  Then  the 
proper  length  of  the  performance  is  predetermined 
and  the  running  speed  noted,  and  the  musical  direc- 
tor arranges  his  music  accordingly. 

With  the  operating  speed  predetermined  the  oper- 
ator starts  his  machine  and  regulates  the  speed  of 
the  projection  machines  in  the  regular  way  by  the 
motor  attachment  until  the  indicator  shows  the  cor- 
rect speed  in  feet  per  minute,  and  in  this  manner 
the  music  and  the  projection  speed  is  synchronized 
and  the  duration  of  the  performance  will  be  the  same 
at  each  showing. 

In  use  in  the  majority  of  leading  theatres  through- 
out the  country  where  it  has  proved  the  value  and 
necessity  of  projecting  pictures  at  the  relative  speed 
as  taken,  with  music  synchronized  to  support  the 
action  of  the  photoplay. 


MOTION     PICTURE     PROJECTION 


149 


Plate  No.  5,  illustrates  switchboard  and  connec- 
tion for  equipment  of  two  projection  machines,  two 
meters  in  the  booth  and  one  for  the  orchestra  pit. 

ROBIN  ELECTRIC  TIME  SYSTEM 
PLATE  5 


RI6HT     MACH    INOOTOR 


1-niitr  SWITCH 


StflTCH    BCMRD 


//Die  }0  HOT  CMfHtt    CAtLC  LCN 
KfBIHS  ClMfMA  [UCTItlC  TIME 


DICATORS  Wff^ftO  GENERATORS 

ATf  Sc*  i  £  rrre  \ 

C4SLC  JOKTH  l*rt  fit  CAC/ftlWC* 


Two  Machines,  Three  Meters  and  Switchboard 


150 


MOTION     PICTURE     PROJECTION 


Plate  No.  6  illustrates  correct  position  for  instru- 
ments with  meter  underneath  the  lookout  holes  and 
which  gives  the  measurements  of  both  and  drilling 
template.  PLATE  6 


PPOJICTICN 

FUr 
0PCMIN* 


LOCATION  or  Mere* 


'jK.NTTei!YttL 

•#/« 

5llt 

tlMTH 

HIP 

y?H 

HOLLOW   TILE 

TOGGLE 

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J" 

CEMENT 

EXPANSION 

BRICK 

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XSBESTOSj 

HtX     HMD 

(V 

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SHEET  IRON 

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5L-4TE.WNEUS 

HEX    CAP 

2" 

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OS£  SPRING  WASHERS  BETWfCNMfTCI 
B*ACKET  AND  NUTS 


J E.ROBIN 


Robin  Speed  Indicator 


MOTION     PICTURE     PROJECTION  151 


'A  Pocket   Reference   Book 

FOR 

Managers  and  Projectionists1 

By  JAMES  R.  CAMERON 


Price  One  Dollar 
THEATRE  SUPPLY  COMPANY 

124  WEST  45TH  STREET  NEW  YORK  CITY 


152 


MOTION    PICTURE     PROJECTION 


PORTABLE  PROJECTORS 

The  portable  projector  has  made  a  permanent 
place  for  itself  in  the  motion-picture  industry,  several 
hundreds  of  this  class  of  machine  are  in  daily  use  in 
studios,  cutting-rooms  and  viewing  rooms,  salesmen 
are  using  them  to  help  sell  their  wares.  Motion  pic- 
tures are  becoming  a  part  of  the  curriculum  in 
churches  and  schools  through  the  medium  of  the  port- 
able projector.  This  type  of  machine  has  been 
brought  to  a  high  stage  of  perfection,  it  is  now  pos- 
sible to  get  a  complete  motor-driven  motion-picture 
machine  enclosed  in  a  carrying  case  measuring  ap- 
proximately 18"xl7"x8"  and  weighing  about  25  Ibs, 
and  this  compactness  has  not  been  obtained  by  sacri- 
ficing accuracy.  Portable  projectors  are  built  along 
various  lines,  each  manufacturer  having  his  own  ideas 


toose  LOOP 
»o  HOTHAve  am 

TOUCH  MAHAIIHf 


MOTION     PICTURE     PROJECTION 


153 


No.  1 

Focusing  button 

No.  2 

Framing  button 


No.  3 

Lamp  switch 

No.  4^ 

P. — Projector 
R.— Rewind 


No.  6  — 

Cord  connection. 

No.  7 

P. — Projector. 
R.— Rewind. 

N.— Neutral 


No.  5 

•  Motor  speed 
control 


154 


MOTION     PICTURE     PROJECTION 


on  this  subject,  and  to  attempt  to  describe  each  type 
in  a  work  of  this  kind  would  prove  to  be  a  hopeless 
task,  we  will  however  devote  a  little  space  to  the 
handy  suitcase  model. 

THE  ACME  PORTABLE  PROJECTOR 

To  those  who  are  at   all  familiar   with   Moving- 
Picture  Projectors,  a  glance  at  the  accompanying 


The  Safety  Shutter  (B)  drops  and  covers  the  aperture  plate 
opening,  cutting  off  the  light  rays,  whenever  the  Acme  is  not 
being  operated.  While  the  machine  is  being  operated  the 
Shutter  is  held  by  centrifugal  force  in  position  shown  by 
dotted  lines  "A."  In  threading  the  film,  the  "pull-out"  (D)  is 
opened  into  position  C,  thus  allowing  the  greatest  accessibility 
in  getting  the  film  in  place.  But  as  soon  as  the  film  is  threaded 
this  "pun-out"  slips  back  into  place  and  is  held  there  by  a  coil 
spring,  preventing  any  of  the  film  from  ever  getting  in  the 
path  of  the  light. 


MOTION"     PICTURE     PROJECTION 


155 


diagrams  will  be  all  the  instruction  required.  To  the 
uninitiated,  however,  a  word  or  two  of  explanation 
may  be  of  advantage. 

Upon  examining  the  film  you  will  find  that  one 
side  has  a  very  dull  finish.  This  is  called  the  emulsion 
side.  The  other  side,  which  has  a  glossy  surface,  is 
known  as  the  celluloid  side.  The  film,  when  properly 
rewound,  must  have  the  emulsion  side  upward. 

When  threading  the  projector,  the  film,  when 
placed  in  the  aperture  plate,  must  be  inverted — that 
is,  show  the  image  "upside  down" — and  with  the  dull 
or  emulsion  side  toward  the  lamp  house. 

To  thread  the  Acme  pull  out  the  round  film  guard 
between  the  gate  marked  No.  4  and  the  lens,  push  down 
the  three  guide  rollers  numbered  3,6  and  7  in  diagram 


Inside  (in  roller. 


Inside  or  Takeup 


156  MOTION     PICTURE     PROJECTION 

"B"  these  are  shown  in  diagram  "C"  in  open  position. 
Next  open  aperture  gate  by  lifting  spring  catch  on 
gate  number  4  towards  you,  this  is  done  through  the 
small  round  hole  in  the  division  plate  between  the 
lamp  house  and  projector.  Next  open  the  magazine 
by  pushing  down  on  the  catch,  swinging  the  outer 
half  outwards  so  that  the  magazine  when  open  hangs 
at  right  angles  from  the  projector,  then  place  the 
full  reel  of  film  on  the  shaft  of  the  outer  magazine, 
turn  clip  on  this  shaft  down  to  keep  reel  in  place. 
Next  draw  the  film  through  the  rollers  and  pull  tow- 
ards you.  The  emulsion  or  dull  side  must  be  face 
upward,  and  three  feet  of  film  should  be  drawn  from 
the  outer  magazine  in  order  to  thread  the  Acme,  then 
partly  close  the  outside  magazine,  place  the  film  over 
the  top  of  stationery  guide  roller  No.  1,  under  film 
sprocket  marked  No.  2  making  sure  that  the  per- 
forations are  over  the  teeth  of  this  sprocket,  then 
push  up  guide  roller  No.  3  into  place;  the  film  is 
in  correct  position  when  it  is  between  sprocket  No.  2 
and  roller  No.  3  as  shown  in  diagram  "B."  Now 
make  a  loose  loop  that  is  also  shown  in  diagram  "B" 
placing  the  film  in  the  aperture  plate  marked  No.  4, 
close  aperture  gate  and  see  that  the  spring  catch  on 
it  is  securely  fastened.  When  the  film  is  placed  in  the 
aperture  plate  correctly  the  picture  must  be  upside 
down  with  the  emulsion  or  dull  side  towards  the 
lamp  house.  The  film  must  now  pass  in  front  of 
sprocket  No.  5  as  shown  in  diagram  "B."  The  perfo- 
rations must  be  engaged  on  the  teeth  of  the  sprock- 
et. When  this  is  done  push  guide  roller  No.  6  into 
position  as  shown  in  diagram  "B."  This  same  dia- 
gram shows  a  loose  loop  between  sprocket  No.  5  and 


MOTION    PICTURE     PROJECTION  157 


If  desired  you  can  change  the  lamp  in  the  Acme  in  a  few 
seconds— merely  slide  it  out  of  its  housing,  as  shown  in  the 
illustration.  Both  up-and-down  and  horizontal  adjustments 
are  made  by  simply  loosening  the  screws,  getting  the  adjust- 
ment you  want,  then  tightening  them  again.  The  Condenser, 
in  case  it  needs  cleaning,  is  easily  removable  by  merely  loosen- 
ing the  two  thumb-screws. 


158  MOTION     PICTURE     PROJECTION 

sprocket  No.  8 ;  this  is  imperative.  This  loop 
must  be  as  large  as  it  can  be  made  without  touching 
the  round  magazine  underneath  it.  Place  the  film 
underneath  the  guide  roller  No.  7  and  over  the  top 
of  sprocket  No.  8.  When  this  is  done  close  guide 
roller  No.  7;  now  you  have  the  projector  mechanism 
threaded — open  the  outer  magazine,  which  can  be 
done  while  the  film  is  in  it.  Place  film  from  sprocket 
No.  8  through  the  slot  of  the  inner  magazine  between 
the  magazine  rollers.  Take  the  end  of  film ;  place  it 
underneath  the  spring  clip  on  the  center  of  the  empty 
reel  hub,  give  it  one  turn  to  securely  fasten  the  film, 
place  this  reel  on  the  inner  magazine  shaft,  be  sure 
that  the  slot  in  this  reel  slides  over  the  key  on  this 
shaft.  When  in  position  turn  down  clip  on  the  end 
of  shaft  to  hold  this  reel  in  place.  The  direction  of 
travel  on  this  inner  reel  is  always  towards  the  right. 
Then  close  outer  magazine,  machine  is  now  ready  for 
operation. 

To  operate,  insert  connection  plug  in  opening 
No.  6  at  back  of  case.  See  that  indicator  on  bottom 
No.  4  points  to  "P,"  (Picture)  ;  also  that  lever  No.  7 
is  at  "P." 

Push  in  the  button  on  switch  No.  3.  This  lights 
the  lamp.  Then  turn  button  No.  5  slowly  to  right. 
This  operates  the  motor  and  any  speed  desired  may 
be  obtained  by  merely  turning  it.  To  stop  machine 
turn  back  to  left. 

Button  No.  1,  on  top  of  the  projector,  operates 
the  focusing  device,  and  if  you  cannot  get  the  image 
sharp  by  turning  this  button,  open  the  case  door  and 
adjust  the  lens  tube  in  the  lens  jacket  by  moving  it 
forward  or  backward  with  your  hand  until  the  right 
effect  is  obtained. 


MOTION     PICTURE     PROJECTION  159 


The  simple  button  (on  outside  of  case)  moves  the  rheostat  up 

and  down,  as  shown  by  the  dotted  line  in  the  illustration,  thus 

giving  practically  any  speed  required. 


160  MOTION     PICTURE     PROJECTION 

Button  No.  2  operates  the  framing  device,  and  by 
turning  in  either  direction  it  enables  you  to  frame 
the  picture  instantly.  If  you  do  not  see  the  full  pic- 
ture on  the  screen,  simply  operate  button  No.  2  to 
locate  correctly. 

To  rewind  after  using,  be  sure  light  is  turned  off; 
take  off  the  full  reel  from  inner  magazine  shaft.  Re- 
move empty  reel  from  outer  magazine.  Stand  full 
reel  on  rim,  with  end  of  film  toward  the  right.  Now 
wind  end  on  hub  of  empty  reel,  dull  side  outward, 
securing  end  firmly  with  a  few  turns.  Now  place 
empty  reel  on  inner  magazine  shaft,  slipping  film 
through  magazine  rollers.  Loop  film  over  the  two 
wooden  rollers  in  top  of  case  as  shown  in  Fig.  "C." 
Turn  down  clip  on  inner  shaft  holding  the  reel  in 


MOTION     PICTURE     PROJECTION 


161 


When  the  reel  has  been  run  through  the  Projector  (and  must 
be  re-wound  to  be  run  again),  you  merely  transfer  the  reels 
on  the  feed  and  takeoff  shafts,  run  the  film  over  the  two 
wooden  rollers,  and  turn  the  button  releasing  the  motor.  None 
of  the  projecting  mechanism  is  used  for  this  purpose,  but  re- 
mains at  a  standstill  during  the  rewinding  operation. 


162 


MOTION     PICTURE     PROJECTION 


place.  Bring  outer  magazine  around  to  closing  posi- 
tion, threading  film  through  magazine  rollers,  placing 
reel  on  shaft,  again  turning  down  clip  on  shaft  to 
hold  reel  in  place.  Close  and  lock  outer  magazine. 
At  back  of  case,  turn  indicator  on  button  No.  4*  to 
"R."— -  Rewind.  Turn  also  lever  No.  7  to  "R."- 
Rewind.  Then  turn  button  No.  5  to  right — slowly 
— to  operate  motor  for  rewinding. 


The  lens  barrel  is  easily  taken  out  through  the  front  opening 
without  having  to  remove  shutter  or  any  other  part.  This  lens 
barrel  merely  slides  into  the  lens  jacket  (A),  and  this  jacket 
is  moved  forward  or  backward  (in  B)  by  the  button  on  top 
of  case.  Correct  focus  for  any  distance  may  be  obtained  by 
sliding  the  lens  either  way  within  this  jacket. 


MOTION     PICTURE     PROJECTION 


163 


Focusing  Button 

Framing 
Button 


Oil  Tube  , 
Cover 


Clutch  


Rear  View  of  Acme  Showing  Adjustments  and  Controls 


164  MOTION     PICTURE     PROJECTION 

Caution 

When  through  rewinding,  always  turn  the  indicat- 
ors on  buttons  No.  4  and  No.  7  to  the  letter  "P" — 
Picture — before  making  ready  for  the  next  pro- 
jection. 

OPERATING  BY  HAND 

To  operate  the  Acme  Projector  by  hand,  all  that 
is  necessary  is  to  move  the  lever  No.  7  to  the  center 
groove  which  releases  the  motor. 

OILING  THE  PROJECTOR 

On  the  top"  of  the  machine  case  you  will  notice  a 
small  oblong  opening  that  has  a  metal  slide  door, 
push  back  this  slide  and  you  will  find  four  oil  tubes 
directly  underneath  it.  These  four  tubes  lubricate 
the  bearings  in  the  back  of  the  mechanism.  The 
motor  has  an  oil  tube  coming  through  the  perforated 
guard  that  leads  to  its  inner  bearing.  The  top  of 
the  fan  has  a  drilled  screw — this  is  for  oiling.  On 
the  end  of  the  fan  bracket  you  will  notice  two  fibre 
pulleys.  Between  these  two  you  will  find  an  oil  hole 
which  lubricates  them.  There  is  an  oil  well  on  the 
outer  end  of  the  motor  which  is  very  accessable. 
The  inside  of  the  two  shafts  in  the  magazine  must 
have  oil — you  will  find  oil  holes  there  for  same.  On 
the  mechanism  you  will  find  on  the  shutter  shaft  two 
nickel  plated  brackets  with  holes  for  lubricating. 
You  will  find  oil  holes  on  Shaft  bearings  of  feed  and 
take-up  sprockets — the  intermittent  sprocket  has  a 
bronze  bushing  with  oil  hole  in  same,  to  get  at  this, 
slide  the  mechanism  forward  as  far  as  it  will  go.  On 
side  of  case  opposite  door  in  about  the  center  close 
to  the  bottom  is  a  round  hard  rubber  bushing,  you 


MOTION     PICTURE     PROJECTION 


165 


SLIDING  COVER" 


On  top  of  the  case  is  a  sliding  cover,  just  beneath  which  are 
five  oil-tubes,  each  leading  directly  to  an  oil-hole  at  some  bear- 
ing. The  motor  shaft  and  belt  pulleys  are  also  provided  with 
similar  oil-tubes.  The  intermittent  mechanism  is  of  the  Geneva 
type  and  runs  in  an  oil  bath.  The  Acme  intermittent  move- 
ment can  be  adjusted  without  having  to  remove  the  mechanism 
from  the  case. 


1G6 


MOTION     PICTURE     PROJECTION 


will  find  the  shaft  for  double  idler  pulley  right  inside 
this  hole;  this  must  have  oil  very  often,  in  fact  all 
bearings  should  have  a  drop  of  oil  each  day  before 
operating  machine. 


, 


Merely  turning  the  button  on  top  of  the  case  in  either  direction 
frames  the  picture  instantly.     The  illustration  shows  that,  in 
framing,  the  aperture  plate  and  lens   remain   absolutely  sta- 
tionary— the  movement,  forward  or  backward,  of  the  mechan- 
ism   adjusts    the    relative    position    of    the    picture    until    it 
"frames"  correctly. 


MOTION     PICTURE     PROJECTION  167 


THE  VENTILATING,  HEATING  AND  COOL- 
ING OF  THEATRES 

Rapid  as  has  been  the  development  of  the  motion- 
picture  theatre,  in  one  department  there  has  been 
but  little  visible  progress — ventilation. 

We  therefor  approached  the  Monsoon  Cooling 
System  of  New  York  City  who  are  experts  on  this 
subject,  and  they  were  pleased  to  have  their  chief 
engineer  Mr.  E.  L.  Garfield  co-operate  with  us  in 
the  preparation  of  a  technical  article  on  the  subject 
of  theatre  ventilation. 

Some  blame  attaches  to  the  exhibitor  because  of 
the  scant  attention  he  has  given  to  this  important 
subject.  But  the  underlying  cause,  to  my  mind,  is 
the  general  lack  of  specialized  knowledge  on  theatre 
ventilation. 

Winter  ventilation,  for  instance,  is  almost  univer- 
sally treated  with  absolute  disregard  for  its  effect  on 
the  heating.  The  natural  result  is  a  house  warm 
enough,  but  ill-smelling  and  stuffy;  or  a  house  with 
a  pure  atmosphere,  but  a  bit  too  chilly  for  comfort. 

The  usual  treatment  of  summer  ventilation  and 
cooling  leaves  out  of  consideration  the  high  percent- 
age of  moisture,  humidity,  to  be  found  in  the  at- 
mosphere in  hot  weather.  And  yet  this  humidity 
causes  more  discomfort  in  a  warm  theatre  than  the 
high  temperature  itself. 

Let  us  first  consider  the  proper  method  of  venti- 
lating a  theatre  in  cold  weather.  It  must  be  recog- 
nized from  the  outset  that  this  is  impossible  without 


168 


MOTION     PICTURE     PROJECTION 


the  loss  of  some  heat.     How  great  this  heat  loss  is 
depends  on : 

1. — The  frequency  of  air  change. 

2. — The  degree   of  scientific  skill  applied  to   the 

problem. 

The  two  generally  accepted  methods   of  heating 

and  ventilating  a  theatre  may  be  classified  as  follows : 

1. — All   direct   radiation   for   heat,   with   exhaust 

fans  for  ventilation. 

2. — Indirect  radiation  or  warmed  air  supply  for 
both  heating  and  ventilation,  combined  with  a 
small  amount  of  direct  radiation. 
Direct  radiation  comprises  the  use  of  the  ordinary 
steam   or  water   radiators,   the  heat   being   applied 
directly  to  the  air  in  the  immediate  vicinity  of  each 
radiator. 

Indirect  radiation  (or  tempered  air  supply)  con- 
sists of  warming  fresh  air  and  forcing  it  into  the 
auditorium  at  one  or  more  points. 


Monsoon  Cooling  Apparatus.     The  Arrows  Show  How  the  Air 
Currents  Reach  Every  Point  of  the  Auditorium 


MOTION     PICTURE     PROJECTION  169 

Mainly  for  reasons  of  economy,  I  would  use  the 
first  method  outlined  above  for  the  smaller  theatre — 
say,  one  up  to  800  seats.  It  is  simple  and  practical. 
With  sufficient  radiation,  properly  distributed,  there 
can  be  no  great  difficulty  in  maintaining  a  fairly 
even  temperature. 

Successfully  to  combine  this  method  of  heating 
with  good  ventilation  demands  careful  study  so  as 
to  effect  the  proper  air  change  with  minimum  heat 
loss,  and  without  objectionable  drafts.  I  have  little 
regard  for  exhausting  at  the  ceiling  line  because  it 
assumes  that  the  warm  air  at  the  ceiling  is  necessari- 
ly foul  air. 

This  is  wrong:  foul  air  is  heavy.  It  has  been 
breathed  and  become  laden  with  moisture,  carbon 
dioxide  and  organic  impurities  thrown  off  by  the 
lungs.  Naturally,  being  heavy,  it  lies  close  to  the 
floor  line;  and  because  it  lies  near  the  floor  line, 
it  is  at  this  point  that  we  must  exhaust  if  we  would 
remove';tfe*foul,  ill-smelling  air. 

Furthermore,  this  heavy  air  does  not  readily  ab- 
sorb heat.  It  is  therefore  the  coldest  air  in  the 
house;  and  if  we  exhaust  it  we  pass  out  with  it  the 
smallest  possible  amount  of  heat.  Consequently, 
from  the  standpoint  of  heat  economy,  it  costs  least 
to  remove  this  air,  while  it  costs  most  to  remove 
air  at  the  ceiling  line. 

With  these  facts  established,  it  is  obvious  that  the 
air  should  be  exhausted  at  the  floor  line  near  the 
stage,  or  at  the  end  opposite  from  the  entrance  doors. 
The  fan  apparatus  should  effect  a  complete  air 
change  within  a  certain  limited  period,  to  be  decided 
on  by  a  competent  ventilating  engineer.  Such  an 


170  MOTION     PICTURE     PROJECTION 

air  change,  calculated  on  ordinary  winter  temper- 
atures, might  prove  too  frequent  during  a  few  un- 
usually cold  periods.  The  thing  to  do  then  is  to  cut 
down  the  air  change  slightly,  in  the  interests  of  heat 
economy  by  reducing  the  speed  of  the  fan. 

The  only  possible  objection  to  this  method  of 
heating  and  ventilating  is  the  possible  slight  tendency 
to  drafts  through  the  doors,  but  this  can  be  compen- 
sated for  by  placing  extra  radiation  at  the  entrances. 

Heating  and  ventilating  in  this  manner  will  pro- 
duce fairly  satisfactory  results,  and  its  cost  is  not 
out  of  proportion  to  the  cost  of  the  average  house 
of  800  seats.  It  could  not  be  improved  upon  except 
by  the  use  of  indirect  heating,  usually  too  expensive 
for  the  small  theatre. 

In  the  larger  house  the  cost  of  indirect  heating 
does  not  loom  up  so  large  in  proportion  to  the  cost 
of  the  complete  building.  In  fact,  the  cost  may  prove 
in  most  cases  to  be  less  that  that  of  diroct  heating. 
And,  certainly,  in  view  of  the  splendid  results,  the 
indirect  method  is  far  more  desirable. 

In  laying  out  an  indirect  heating  aiid  ventilating 
system  for  the  larger  house,  warm  air  supply  units 
are  located  at  the  stage  end  (opposite  from  the  en- 
trance doors).  These  supply  the  required  amount 
of  fresh  air  at  a  temperature  of  70°  or  over.  It 
is  imperative  that  large  fans  be  used,  so  that  the 
apparatus  can  be  run  at  low  speed,  handling  the  air 
at  low  velocity,  thus  insuring  absence  of  drafts,  of 
noise  and  of  vibration. 

The  fresh  air  supply  is  taken  at  least  20  feet  above 
ground  level,  so  that  it  is  pure  and  free  from  dust. 
In  this  way,  we  eliminate  the  necessity  for  an  air- 


MOTION     PICTURE     PROJECTION  171 

washer,  which  is  expensive,  requires  constant  atten- 
tion and  is  objectionable  for  other  reasons.  The 
roof  or  the  attic  is  usually  the  best  location  for  the 
heating  and  ventilating  equipments. 

The  air  blown  into  the  theatre  finds  its  way  out 
through  openings  at  the  floor  line  but,  to  insure 
positive  circulation,  exhaust  fans  are  sometimes  ad- 
visable. A  large  part  of  the  air  supplied  naturally 
passes  out  through  the  entrance  doors  and  also 
through  openings  in  the  rear  of  the  balcony,  if  there 
is  one.  The  fundamental  principle  is  to  keep  re- 
moving the  air  from  the  floor  line  or  breathing  zone, 
and  to  allow  the  warm,  fresh  air  blown  in  to  settle 
like  a  blanket  of  warmth  evenly  over  the  entire  audi- 
torium. 

Two  desirable  advantages  that  appeal  instantly  to 
the  theatre  manager  are  these: 

1. — No  inrush  of  cold  air  from  outdoors  when  the 
entrance  doors  are  open.    On  the  contrary,  an 
outward  motion  of  warmed  air,  due  to  slight 
pressure  maintained  by  heating  fans. 
2. — House  heated  very  rapidly  before  opening,  as 
theatre  air  can  be  passed  and  re-passed  several 
times  through  heaters  (re-circulated). 
Such  a  system  is  all  that  is  required  during  the 
time  that  the  auditorium  is  occupied  by  the  audience. 
However,  it  would  be  well  to  provide  some  direct 
radiation  to  allow  for  heat  losses  through  exposed 
walls,  although  the  heat  radiated  by  persons  in  the 
audience  will,  in  a  large  measure,  compensate  for  this 
particular  heat  loss. 

This  small  amount  of  direct  radiation  is  also  of 
good  use  at  times — overnight,  particularly — when 


172 


MOTION     PICTURE     PROJECTION 


the  temperature  falls  below  freezing  point,  with  dan- 
ger to  water  pipes,  etc.  For  this  we  need  just  enough 
direct  radiation  to  keep  the  temperature  at  35°  F, 
as  it  is  not  economical  to  run  the  fans  for  heating 
when  the  theatre  is  not  occupied  and  ventilation  is 
not  required.  The  dressing-rooms,  toilets,  rest- 
rooms,  etc.,  have  the  usual  direct  radiation. 

Extremely  cold  weather  that  falls  below  normal  is 
unusual  and  generally  of  short  duration.  For  this 
reason,  it  is  not  a  great  hardship  to  sacrifice  a  small 
part  of  our  fresh  air  supply  for  fuel  economy,  par- 
ticularly as  the  system  is  designed  for  maximum  fresh 
air  supply  and  therefore  permits  of  some  reduction. 
During  these  periods  some  of  the  warm  air  already 
blown  into  the  theatre  is  brought  back  to  the  heating 
units  and  mixed  with  fresh,  outdoor  air.  By  the  use 
of  an  arrangement  of  dampers,  it  is  possible  to  ob- 
tain a  mixture  of  fresh  air  and  re-circulated  air  in 
proportion  to  meet  any  unusual  drop  in  temperature. 
This  feature  is  utilized  only  during  the  few  short 
periods  of  extreme  cold. 


Monsoon  Cooling  Apparatus  Installed  in  Large  Theatre 


MOTION     PICTURE     PROJECTION  173 

When  absolutely  perfect  results  are  desired — and 
finances  permit — a  profitable  investment  is  a  system 
of  thermostatic  control  of  mixing  dampers,  a  thermo- 
static  control  of  steam  valves,  or  a  combination  of 
both.  With  this  system  the  lower  the  temperature, 
the  greater  the  quantity  of  theatre  air  re-circulated 
and  mixed  with  fresh  air.  On  the  other  hand,  a  rise 
in  temperature  is  accompanied  by  an  automatic  shut- 
ting off  of  steam  in  part  of  the  indirect  heaters,  so 
reducing  the  temperature  of  the  fresh  air  supply.* 

And  now  summer  ventilation  and  cooling.  At  this 
season  of  the  year  an  enormous  quantity  of  moisture 
is  thrown  off  by  the  human  body,  and  the  problem 
then  becomes  one  of  removing  the  air  in  such  volume 
as  to  remove  with  it  this  moisture  as  rapidly  as  it  is 
formed. 

Actually,  there  is  no  binding  necessity  to  lower  the 
temperature.  The  point  at  issue  is  to  make  the 
human  body  comfortable,  and  this  can  easily  be  done 
by  creating  a  breeze,  passing  it  over  and  around 
every  person  in  the  audience  and  carrying  away  the 
bodily  heat  and,  especially,  evaporating  the  moisture 
constantly  forming  on  the  skin.  It  is  simply  taking 
advantage  of  an  old  principle,  the  practical  working 
efficiency  of  which  is  convincingly  demonstrated  every 
time  a  perspiring  person  takes  a  trolley  or  auto- 
mobile ride  on  a  hot  day.  It's  the  breeze  that  cools. 
It  can  be  nothing  else,  since  the  temperature  is  no 
lower. 

The  cost  of  cooling  by  the  breeze  method  is  very 
small  in  comparison  with  the  lower  temperature 
method.  All  that  is  necessary  is  sufficient  fan  capac- 
ity to  effect  a  very  rapid  air  change — from  ten  to 


174  MOTION     PICTURE     PROJECTION 

fifteen  times  that  required  for  winter  ventilation. 
It  will  be  found  that  this  is  sufficient  to  create  a 
perceptible  movement  of  air  that  will  prove  entirely 
satisfactory.  It  may  be  honestly  advertised  as  a 
"cooling  system"  and  can  be  depended  upon  to  keep 
the  house  comfortable  in  the  hottest  summer  weather. 

As  with  the  winter  ventilation,  best  results  can  be 
expected  only  if  the  "cooling  system"  is  laid  out  by 
a  competent  engineer  who  has  had  practical  experi- 
ence in  this  line  of  work.  Unless  this  precaution  is 
taken,  there  can  be  no  safe  assurance  that  the  air 
currents  are  evenly  distributed  over  the  house — 
that  the  breezes  can  be  felt  throughout,  that  they 
are  not  too  strong  in  some  quarters  as  to  be  ob- 
jectionable. 

It  is  equally  important  that  a  fan  apparatus  be 
specified  designed  specially  for  moving  tremendous 
volumes  of  air  at  low  velocity  and  operating  slowly 
enough  to  be  silent. 

An  economical  arrangement,  for  a  theatre  under 
construction  is  to  arrange  the  fan  apparatus  so  that 
part  of  the  cooling  and  ventilating  fans  are  used 
with  the  indirect  heaters  to  form  the  heating  and 
ventilating  units  for  winter  operation.  Or,  stated 
the  other  way,  the  fans  used  in  the  heating  and  venti- 
lating units  may  also  be  used  for  cooling  in  summer, 
in  combination  with  auxiliary  cooling  equipment  to 
give  the  additional  air  volume  required  in  hot 
weather. 

The  cooling  and  ventilating  system  alone,  without 
heating,  can  be  installed  in  any  theatre,  no  matter 
how  old,  at  any  time. 


MOTION     PICTURE     PROJECTION  175 

Ventilation  of  theatres  is  now  receiving  more  atten- 
tion than  ever.  And  the  time  is  coming — soon,  too- — 
when  the  problem  of  ventilating  will  receive  fully  as 
much  attention  as  any  other  connected  with  the  de- 
signing and  building  of  theatres. 

Hot  weather  cooling,  too,  will  receive  more  con- 
sideration. And  why  not?  If  it  is  profitable  to 
heat  a  theatre  in  winter  to  attract  or  keep  business, 
why  not  cool  the  house  in  •  summer  for  the  same 
reason? 

As  the  importance  of  these  subjects  is  better  ap- 
preciated, it  will  be  realized  more  and  more  that  they, 
should  be  handled,  not  by  hit-or-miss  guesswork,  but 
by  competent  engineers  who  know  by  scientific  train- 
ing and  experience  what  is  needed  and  how  to  pro- 
vide it. 


176  MOTION     PICTURE     PROJECTION 


Accessories  and  Profits 

Inter-Ocean  Film  Corporation  is  the  oldest 
film  accessory  company  in  the  world. 

What  does  this  mean?  It  means  protec- 
tion for  the  buyer  inasmuch  as  no  accessory 
organization  could  stay  in  business  which  was 
not  supplying  its  vast  army  of  customers 
with  the  right  accessories — at  the  right  price. 

Inter-Ocean's  whole  success  has  been 
founded  on  its  ability  to  deliver  a  quality 
product  at  a  reasonable  price.  Inter-Ocean 
Film  Corporation  has  been  prospering  be- 
cause it  has  been  serving. 

Let  Inter-Ocean  serve  you.  A  complete 
line  of  high  quality  accessory  products  are 
available  at  the  Inter-Ocean  offices. 


ACCESSORY  DEPARTMENT 

INTER-OCEAN    FILM    CORPORATION 

218  West  42nd  Street 
New  York  City 


MOTION    PICTURE     PROJECTION  ITT 


Accessories  and  Profits 

There  are  no  projector  carbons  like  Speer 
Carbons.  Nor  is  there  a  better  projector 
than  the  Master  Projector.  The  Fulco  line 
of  over  three  hundred  standard  articles  is 
unparalleled.  Wohl  Studio  Equipment  fur- 
nishes a  striking  example  of  economical  and 
practical  studio  accessories.  In  addition  to 
the  above-named  accessory  products,  Inter- 
Ocean's  list  of  products  includes  the  well- 
known  Hawk  Spotlight,  Argus  products  and 
Westinghouse  incandescent  lamps. 

Inter-Ocean  invites  correspondence  from 
prospective  buyers  of  motion  picture  acces- 
sory products. 


ACCESSORY  DEPARTMENT 

INTER-OCEAN    FILM    CORPORATION 

218  West  42nd  Street 
New  York  City 


178  MOTION    PICTURE     PROJECTION 


AUTOMATIC  ARC  CONTROLS 

The  hand-fed  arc  is  fast  losing  favor,  most  thea- 
tres are  now  equipping  their  projectors  with  arc  con- 
trols. There  are  various  makes  of  arc  controls  on 
the  market,  but  as  it  has  been  the  lot  of  the  writer 
to  have  seen  the  Peerless  automatic  controller  under 
various  stages  of  manufacture  and  to  have  been  in 
close  touch  with  them  under  actual  working  con- 
ditions in  various  Broadway  theatres  we  shall  take 
the  liberty  of  discussing  this  special  type  in  these 
pages. 

This  Control  is  made  for  use  on  all  makes  of  pro- 
jectors having  Direct  Current  at  the  arc,  and  will 
operate  equally  well  with  current  supplied  by  a 
Motor  Generator,  Converter,  Mercury  Arc  Rectifier 
or  110  volt  D.C.  from  the  power  companies. 

The  instrument  is  designed  to  stand  on  the  floor 
at  the  rear  of  the  projector,  the  power  being  trans- 


Peerless  Automatic  Arc  Control  Before  Assembling 


MOTION     PICTURE     PROJECTION  179 

mitted  from  the  motor  mounted  on  the  Control  to 
the  feed  handle  of  the  arc  lamp  by  means  of  a  tele- 
scoping tube  and  shaft  that  automatically  adjusts 
itself- for  the  various  height  projectors. 

A  complete  feed  handle  assembly  shown  in  the 
accompanying  line  drawing,  consisting  of  the  parts 
M,  J,  N,  F,  P  with  a  worm  gear  and  worm  mounted 
thereon  is  supplied  as  a  part  of  the  Peerless  Control, 
and  replacing  the  regular  feed  rod  and  handle  on  the 
projector. 

The  actuating  element  is  completely  enclosed  and 
the  entire  device  is  approved  by  the  Underwriters 
Laboratories  Inc.,  their  approval  number  E-4988. 

The  operation  of  the  Control  is  governed  by 
changes  in  the  arc  voltage  there  being  two  highly 
sensitive  magnets  in  series  with  each  other  connected 
directly  across  the  line  in  multiple  with  the  arc  and 
their  strength  varies  directly  proportionate  to  the 
variation  in  the  arc  voltage.  These  magnets  influence 
an  armature  carrying  contact  points  having  a  gap 
of  approximately  ".006",  and  to  the  armature  is 
connected  a  spring  which  in  turn  is  attached  to  the 
adjusting  screw  marked  "A"  on  the  accompanying 
line  cut.  The  various  length  arcs  may  be  obtained 
by  screwing  in  or  out  this  adjusting  screw. 

These  contacts  open  and  close  a  circuit  to  the 
special  wound  series  type  motor.  It  will  be  readily 
seen  that  when  the  attraction  of  the  magnet  exceeds 
the  opposite  pull  on  the  spring  attached  at  the  end 
of  the  screw  "A"  that  the  armature  will  move  toward 
the  magnet  and  the  circuit  close  with  the  result  that 
the  motor  rotates  and  feeds  the  carbons  together  un- 
til the  arc  voltage  has  decreased  and  in  turn  the 


180  MOTION     PICTURE     PROJECTION 

magnetic  strength  of  the  magnets  decreased  to  a 
point  where  the  spring  is  the  stronger,  with  the 
result  that  the  circuit  is  opened. 

Due  to  the  type  of  construction  employed  in  the 
manufacture  of  this  element,  a  degree  of  sensitiveness 
of  less  than  1/5  of  one  volt  is  obtained,  that  is  to 
say,  that  an  increase  in  the  arc  voltage  of  less  than 
1/5  of  one  volt  above  the  point  for  which  the  ad- 
justment is  set  will  close  the  circuit.  Thus  securing 
a  delicacy  and  fineness  of  operation  that  is  truly  re- 
markable. 


Showing  the  Arc  Controls  Connected  to  Projector  Arc  Lamp 


MOTION     PICTURE     PROJECTION  181 

A  gear  reduction  through  two  sets  of  worm  gears 
one  on  the  Control  itself  and  the  other  on  the  feed 
handle  provides  a  gear  ratio  of  6400  to  one,  with 
the  result  that  the  movement  of  the  carbons  can 
scarcely  be  detected  with  the  naked  eye,  and  insures 
against  any  disturbances  on  the  arc  crater,  as  would 
be  the  case  where  they  moved  rapidly  such  as  is  so 
often  the  practice  with  the  hand-fed  arc. 

A  high  resistance  unit  is  connected  in  series  with 
the  motor,  permitting  some  current  to  enter  the 
motor  at  all  times  when  the  knife  switch  of  the  pro- 
jector is  closed.  This  resistance  serves  the  purpose 
of  reducing  to  a  minimum  the  load  which  the  circuit 
breaker  has  to  break  and  acts  as  a  discharge  coil  as 
well,  thus  eliminating  any  destructive  spark. 

The  automatic  arc  controls  have  been  on  the 
market  long  enough  to  have  their  general  merit  well 
proven  and  taken  altogether  are  highly  recommended 
for  use  in  theatres  desiring  high  grade  screen  results. 

INSTRUCTIONS    FOR    INSTALLING    AND 
OPERATING  THE  PEERLESS  AUTO- 
MATIC ARC  FEED 

This  control  is  made  for  use  on  projectors  using 
Direct  Current  at  the  arc  only. 

Carefully  unpack  the  control  from  the  box  con- 
taining it,  and  remove  all  parts.  Place  the  instru- 
ment on  the  floor  directly  beneath  the  arc  feed 
handle.  Attach  the  nickle-plated  tube  (shown  as 
"B"  on  the  blue  print)  to  the  gear  shaft  universal 
joint  by  means  of  the  screw  and  nut  furnished,  and 
insert  the  shaft  "G"  into  the  tube. 


182 


MOTION     PICTURE     PROJECTION 


If  the  arc  control  is  to  be  used  on  a  Powers,  Motio- 
graph  or  Type  "S"  Simplex  arc  lamp,  remove  the 
arc  feed  handle  and  rod  and  replace  with  the  comp- 
lete assembly  furnished  with  the  control  same  as  it 
is  received. 

If  the  control  is  to  be  used  with  the  "regular" 
type  Simplex  arc  lamp,  having  the  feed  rod  rigidly 
attached  to  the  arc  lamp,  it  is  only  necessary  to 
remove  the  Simplex  fibre  handle  and  in  its  place  as- 
semble the  parts  shown  as  "N",  "J",  "M"  and  the 
gears,  collars,  etc.  onto  the  Simplex  rod. 


MOTION     PICTURE     PROJECTION  183 

Drill  a  small  hole  in  the  rear  of  the  lamp  house, 
about  five  inches  below  the  opening  for  the  arc  feed 
rod  and  insert  the  anchor  "F",  or  attach  anchor  to 
one  of  the  adjusting  rods  by  means  of  clips  furnished. 

Attach  the  universal  joint  at  the  end  of  the  rod 
"G"  to  the  shaft  "H"  on  the  feed  handle. 

The  control  is  then  ready  for  the  electrical  con- 
nections. Bear  in  mind  that  the  Peerless  control  is 
a  voltage-governed  device  and  is  actuated  by  changes 
in  voltage  at  the  arc,  caused  by  the  increase  in  the 
arc  gap  due  to  the  consuming  of  the  carbons.  It  is 
necessary,  therefore,  that  the  device  be  connected  in 
multiple  with  the  arc,  and  at  a  place  in  the  lamp 
circuit  where  it  will  receive  current  after  it  has  pas- 
sed through  the  rheostat  or  motor-generator,  as 
shown  on  the  blue  print. 

Attach  a  snap  switch  and  a  fuse  block,  shown  as 
"K"  and  "L"  on  the  print,  at  a  convenient  place  at 
the  rear  of  the  projector,  a  good  place  being  at  the 
side  of  the  arc  lamp  knife  switch  box,  as  illustrated. 
Encase  the  wires  "C"  and  "D"  in  flexible  Greenfield 
conduit  "O"  and  run  to  the  switch  and  make  con- 
nections. From  the  switch  "K"  run  wires  to  inside  of 
knife  switch  "R"  cabinet  and  connect  to  each  of  the 
arc  feed  wires  as  shown,  being  sure  that  the  current 
which  will  enter  the  control  at  this  point,  has  al- 
ready passed  through  the  rheostat  or  motor-gener- 
ator. 

See  that  the  snap  switch  "K"  is  "off"  and  strike 
the  arc  and  allow  it  to  burn  until  the  crater  has 
properly  formed  on  the  carbons.  Bring  the  carbons 
together  to  the  arc  gap  which  you  wish  maintained, 
turn  on  the  switch  and  loosen  knurled  clamping  screw 


184  MOTION     PICTURE     PROJECTION 

"J"  on  the  feed  handle.  If  the  motor  runs  when  the 
carbons  are  at  the  gap  desired,  slowly  screw  out  the 
arc  gap  adjusting  screw  "A"  until  the  motor  stops. 
Any  arc  gap  desired  may  then  be  obtained  by  screw- 
ing in  or  out  the  screw  "A", — in,  to  shorten  the  gap 
and  out,  to  lengthen  it.  The  control  will  automatic- 
ally maintain  the  arc  gap  for  which  screw  "A"  is 
set,  and  further  adjustment  of  it  is  not  needed  and 
its  position  should  not  be  changed. 

When  putting  a  new  trim  of  carbons  in  the  lamp, 
allow  them  to  burn  in  before  turning  on  the  snap 
switch  "K",  as  the  voltage  at  the  arc  is  much  lower 
than  normally  until  craters  have  formed,  which  would 
result  in  the  control  failing  to  feed  until  the  craters 
had  formed  and  the  voltage  raised  to  normal  at  the 
desired  gap. 


MOTION     PICTURE     PROJECTION 


185 


POWER'S  TYP"E»  LAMPHOUSE  AND  LAMP 

The  Nicholas  Power  Company  have  incorporated 
many  new  features  in  the  new  typ"E"  lamp  and 
lamphouse.  The  proportions  of  the  lamphouse  are 
imposing,  the  extra  large  area  facilitates  an  opera- 
tor in  being  able  to  get  inside  the  lamphouse  to  get 
at  any  adjustment  of  the  arc  lamp.  Two  openings 
in  the  front  of  lamphouse  allows  it  to  be  easily  and 
readily  cleaned. 

Of  paramount  importance  is  the  ventilation  of  the 
lamphouse,  hundreds  of  dollars  are  wasted  annually 
in  condenser  breakage  solely  on  account  of  poor  ven- 
tilation in  lamphouses. 

The  typ"E"  lamphouse  is  so  constructed  to  make 
the  ventilation  scientifically  correct. 


Type  "E"  Lamphouse  and  Lamp  showing  Inside  Dowser 


186  MOTION     PICTURE     PROJECTION 


6B.     Equipment  with  Typ"E"  Lamphouse  complete  with 
Lamp  Assembled 


MOTION     PICTURE     PROJECTION  187 

The  condenser  mount  is  mounted  on  a  heavy  grey 
iron  frame  hinged  to  the  lamphouse  to  open  forward, 
this  allows  the  operator  to  bring  the  whole  con- 
densing set  easily  into  full  view  for  cleaning,'  etc. 
The  condenser  holders  are  made  of  an  extra  heavy 
type  of  grey  iron  so  constructed  that  the  expansion 
and  contraction  of  the  holders  are  fairly  even  and 


Close-Up  of  Condenser  Mount  and   Holder,  and  Adjustment 
for  Inside  Dowser 

that  the  heating  and  cooling  off  of  the  condensers 
is  accomplished  gradually  and  evenly,  this  is  a  very 
important  point  and  helps  in  a  great  way  to  over- 
come condenser  breakage. 

To  assure  the  condenser  proper  alignment  and 
hold  them  securely  in  place,  they  are  machined  with 
a  "V"  on  two  sides,  fitting  into  a  "V"  groove  on  the 


188  MOTION     PICTURE     PROJECTION 

mount.  Placed  directly  under  the  condenser  mount 
is  an  adjustment  which  controls  the  back  condenser 
(one  nearest  the  arc)  allowing  the  operator  to  space 
his  condensers  to  the  exact  local  distance. 

The  lamphouse  is  equipped  with  an  inside  dowser 
to  protect  the  condensers  from  the  heat  of  the  arc 
while  the  operator  is  "forming  a  crater,"  etc.,  the 
dowser  handle  is  placed  on  front  of  the  lamphouse 
directly  above  the  condenser  mount  locking  adjust- 
ment. Radical  changes  have  been  made  in  the  arc 
lamp,  it  is  built  heavy  enough  to  take  care  of  any 
amount  of  current  up  to  150  amperes ;  the  features 
of  the  lamp  are  as  follows : 

1 — Upper  carbon  holder  designed  to  take  from  % 
to  1%-inch  carbon.  Lower  carbon  holder  5/16- 
inch  to  %-inch  carbons,  manufactured  with  the  "V 


Condenser  Holder,  Ring  and  Key 


MOTION     PICTURE     PROJECTION 


189 


type,  assuring  a  rigid  hold  on  the  carbons  without 
breaking  them. 


Upper  and  Lower  Carbon  Holder  showing  "V"-shaped  inserts 
and  inter-locking  corrugations  for  clamping  wires 

2 — Both  upper  and  lower  carbon  holders  are 
equipped  with  a  clamp  which  is  to  take  the  place  of 
lugs  for  the  wires.  These  clamps  have  been  so  manu- 
factured of  a  series  of  interlocking  corrugations  on 
both  top  and  bottom  of  clamp  so  that  when  wires 
have  been  clamped  between  them,  they  will  have  a 
positive  hold.  To  take  care  of  any  possible  arcing, 
the  clamp  and  the  carbon  holder  have  been  manufac- 
tured of  one  piece. 

3 — Another  feature  of  the  lamp  is  the  fact  that 
the  lateral  and  backward  and  forward  adjustments 
are  made  on  the  lower  part  of  the  lamp  so  that  on 


Cross  Section  of  Carbon  Holder  showing  Position  of  Wire  in 
Inter-Locking  Corrugations 


190 


MOTION     PICTURE     PROJECTION 


adjusting  the  carbons,  it  will  not  change  the  posi- 
tion of  the  crater  of  the  upper  carbon. 

4 — The  fact  that  the  raising  and  lowering  of  the 
lamp  is  done  by  means  of  a  worm  wheel  and  gear, 
gives  the  lamp  additional  rigidity. 

5 — Square  steel  bars  held  with  a  spring  cover 
have  been  used  in  the  manufacture  of  the  rack  rods, 
to  take  care  of  any  expansion  and  giving  same  a 
greater  wearing  surface. 


Typ"E"  Lamp.     Note  that  the  top  carbon  is  stationary.    The 

lateral  and  back  and  forward  adjustments  are  made  on 

lower  carbon 


MOTION     PICTURE     PROJECTION  191 


Power's  Cameragraph  No.  6B 


192  MOTION     PICTURE     PROJECTION 


THE  INTERMITTENT  MOVEMENT 
PRELIMINARY  REMARKS 

The  moving  picture  is  accomplished  by  flashing  a 
great  number  of  stationary  photographic  views  be- 
fore the  eye  in  such  rapid  succession  that  the  eye  is 
deceived  into  the  belief  of  having  beheld  actual  mo- 
tion. 

The  photographic  views,  which  are  usually  taken 
at  the  rate  of  sixteen  per  second,  are  printed  in 
direct  succession  upon  a  ribbon  of  transparent  film 
one  and  three-eighths  inch  in  width  and  between  one 
and  two  thousand  feet  in  length.  Each  view  is  con- 
densed into  a  rectangular  space  approximately  one 
inch  wide  and  three-fourths  inch  high. 

When  the  film  is  run  through  the  projector  at  nor- 
mal speed,  sixteen  of  these  views  are  shown  each 
second.  It  would  appear  from  this  that  each  view 
is  shown  for  one-sixteenth  of  a  second.  Such  is  not 
the  case,  however.  Each  view  is  held  stationary 
before  the  lens  for  only  a  part  of  this  minute  period 
of  time,  and  the  remainder  of  the  period  is  consumed 
while  the  film  is  being  moved  down  a  distance  of 
three-fourths  of  an  inch,  so  as  to  bring  the  succeed- 
ing view  in  line  with  the  lens. 

During  every  such  movement  of  the  film,  the  main  , 
blade  (or  wing)  of  a  revolving  shutter,  passes  in 
front  of  the  lens,  thus  preventing  any  trace  of  the 
movements  from  reaching  the  screen.  If  this  were 
not  done,  the  picture  would  be  greatly  marred  by 
streaks  of  light  known  as  "travel  ghost."  An  addi- 
tional wing  (and  sometimes  two)  is  inserted  in  the 


MOTION     PICTURE     PROJECTION 


193 


shutter  wheel  for  the  purpose  of  doing  what  is  tech- 
nically known  as  "equalizing  the  light."  We  will 
not  discuss  this  matter  of  light  equalization,  as  it 
has  no  direct  bearing  upon  the  point  that  we  wish 
to  bring  out. 


It  is  the  necessary  passage  of  these  wings  in  front 
of  the  lens  that  prevents  an  attainment  equalling 
theoretical  perfection  wherein  each  view  would  ap- 
pear on  the  screen  for  its  entire  allotment  of  one- 
sixteenth  of  a  second  without  interruption  of  any 
kind. 


194 


MOTION    PICTURE     PROJECTION 


It  would  probably  be  possible  to  devise  a  way  to 
move  the  film  so  rapidly  that  the  eye  could  not  per- 
ceive any  trace  of  the  movement,  and  thus  the  neces- 
sity of  using  the  revolving  shutter  would  be  eliminat- 
ed, but  we  are  prevented  from  doing  this  by  the  very 
important  fact  that  wear  and  tear  on  the  film  must 
be  taken  into  consideration.  The  movement  of  the 


Fig.  a 


film  must  not  be  made  so  rapidly  nor  in  such  a 
jerky  manner  as  to  cause  the  film  to  rip  or  pull 
apart. 

TECHNICAL  DESCRIPTION  OF  THE 
INTERMITTENT  MOVEMENT 

The  term  "intermittent  movement"  is  used  to  des- 
ignate that  part  of  the  mechanism  of  a  moving  pic- 
ture projector,  which  performs  the  important  func- 


MOTION     PICTURE     PROJECTION 


195 


tion  of  stopping  the  film  at  regular  intervals,  so 
that  the  photographic  views  may  be  successively 
held  in  line  with  the  lens. 

This  movement  consists  primarily  of  four  elements, 
namely:  a  diamond  shaped  cam,  a  locking  ring,  a 
pin  cross  and  a  sprocket.  Photographic  views  of 
these  parts  will  be  found  on  page  193. 

The  cam  and  locking  ring  are  formed  together  on 
the  face  of  a  solid  steel  disc.  The  four  pins  of  the 
pin  cross  are  formed  from  the  end  of  a  solid  cylinder 
of  steel.  The  remainder  of  this  cylinder  is  turned 
down  to  the  proper  diameter  to  act  as  a  spindle 
upon  which  the  sprocket  is  securely  fastened.  The 
sprocket  has  two  rows  of  teeth  to  mesh  with  the 
holes  that  are  perforated  on  each  side  of  the  film. 

Figures  a,  6,  c,  and  d,  show  these  elements  in  ac- 
tion. A  portion  of  the  back  of  the  cam-ring  disc 


Fig.  b 


196 


MOTION     PICTURE     PROJECTION 


has  been  cut  away  so  as  to  expose  the  workings  of 
the  movement  during  one  revolution  of  the  disc.  The 
curved  arrows  indicate  the  direction  in  which  the 
parts  are  revolving.  The  sprocket  is  in  mesh  with 
a  short  strip  of  film.  Portion  e  of  this  film,  which 
lies  between  the  heavy  black  cross  lines,  represents 
one  of  the  photographic  views  to  be  projected  upon 
the  screen. 


Fig.  c 

In  Figure  o,  the  four  pins  of  the  pin  cross  are 
shown  in  engagement  with  the  locking  ring.  Pins  1 
and  2  are  at  the  outer  circumference  and  pins  3  and 
4  are  at  the  inner  circumference  of  the  ring.  Although 
the  ring  is  revolving,  it  cannot  impart  motion  to  the 
pin  cross,  as  the  pins  are  securely  locked  by  contact 
with  the  inner  and  outer  surfaces  of  the  ring ;  conse- 
quently the  pin  cross,  the  sprocket  and  the  film  are 


MOTION     PICTURE     PROJECTION 


197 


at  rest.  It  is  during  this  period  of  rest  that  the 
photographic  view  is  being  projected  on  the  screen. 

In  Figure  6,  the*  pins  are  disengaging  from  the 
locking  ring.  The  cam  is  just  starting  to  engage 
with  pin  1.  As  the  engagement  takes  place  the  pin 
is  pushed  forward  and  upward,  thus  imparting  a 
rotary  motion  to  the  pin  cross  spindle.  The  sprocket, 
being  fastened  to  this  spindle  rotates  with  it,  thus 
pulling  the  film  downward. 

In  Figure  c,  pin  1  has  almost  reached  the  apex 
of  the  cam.  Pin  2  is  traveling  into  slot  f,  pin  3  is 
describing  an  arc  in  the  space  between  the  ends  of 
the  locking  ring,  and  pin  4  is  traveling  out  of  slot  g. 
As  piir-l  slides  over  the  apex  of  the  cam,  pin  4  en- 
gages with  the  curved  surface  h  at  the  end  of  the 
locking  ring,  and  the  pin  is  thrown  forward  and 
upward  until  it  slides  on  to  the  outer  surface  of  the 
locking  ring. 


Fig.  d 


198  MOTION     PICTURE     PROJECTION 

In  Figure  d,  pin  4  has  just  reached  the  outer  sur- 
face of  the  ring.  The  four  pins  are  immediately 
locked  as  the  locking  ring  travels  into  the  space 
between  them.  In  contrast  to  the  pin  position  in 
Figure  a,  pins  1  and  4  are  now  at  the  outer  circum- 
ference and  pins  2  and  3  are  at  the  inner  circum- 
ference of  the  locking  ring.  It  can  readily  be  seen 
that  the  pin  cross  spindle  has  made  a  quarter  revolu- 
tion, and  that  view  e  has  been  drawn  downward  a 
corresponding  distance. 

Bear  in  mind  that  these  pins  can  only  move  in  the 
path  of  a  circle.  As  pins  2  and  4  travel  through 
their  respective  slots  it  would  appear  to  the  unini- 
tiated mind  as  though  the  pins  must  travel  in  a 
straight  line.  This  is  not  the  case,  however.  The 
fact  that  the  cam-ring  disc  is  revolving,  constantly 
changes  the  position  of  these  slots  so  that  their 


MOTION     PICTURE     PROJECTION  199 

straight  lines  intersect  the  circular  path  of  the  pins 
at  successively  different  points. 

One  great  advantage  that  this  particular  move- 
ment has  to  offer,  may  be  demonstrated  by  making 
the  following  simple  experiment: 

Tie  a  one  foot  length  of  ordinary  cotton  thread  to 
a  piece  of  metal  weighing  slightly  over  one  pound. 
Take  the  untied  end  of  the  thread  between  the  fingers 
and  by  an  upward  pull,  endeavor  to  lift  the  piece  of 
metal  a  distance  of  one  foot  in  the  shortest  possible 
time.  A  sudden  jerk  will  snap  the  thread.  A  slow 
upward  pull  will  allow  the  thread  to  stand  the  strain 
of  the  weight,  but  considerable  time  is  consumed  in 
lifting  the  metal.  If  the  slow  pull  is  exerted  until 
the  metal  has  started  to  move,  the  pull  may  then  be 
steadily  increased,  and  consequently  the  metal  can 
be  lifted  much  more  quickly. 

This   analogy   may   be   applied   to   the   star   and 


Intermittent  Movement  with  Oil-Tight  Casing 


200  MOTION     PICTURE     PROJECTION 

cam  intermittent  movement,  which  has  been  care- 
fully designed,  to  move  the  film  downward,  by  start- 
ing the  motion  with  a  scarcely  perceptible  pull  that 
steadily  increases  to  a  maximum  as  pin  1  (Figure  c) 
slides  over  the  apex  of  the  cam,  after  which  it  de- 
creases in  the  same  steady  manner  until  the  pins  are 
locked  by  the  ring,  and  the  film  is  again  at  rest.  Not 


A  magnified   view  of  the   pin   cross   of  the   Power's   Machine, 
with  and  without  roller  bearings  in  place 

a  moment  of  time  is  lost,  and  yet  the  film  is  moved 
so  easily  that  the  wear  and  tear  is  reduced  to  a 
minimum. 

The  elements  of  the  intermittent  movement  are 
made  from  carefully  selected  tungsten-chromium 
steel,  which  is  very  tough  and  durable.  The  most 
delicate  instruments  are  used  in  measuring  the  dimen- 


MOTION    PICTURE     PROJECTION  201 

sions  of  the  elements,  one  ten-thousandth  of  an  inch 
plus  or  minus  being  the  limit  of  permissible  variation. 
The  cam  and  pin  cross  are  enclosed  in  an  oil-tight 
casing.  An  oil  cup  is  fastened  to  this  casing,  and  by 
keeping  the  parts  plentifully  supplied  with  a  high 
grade  machine  oil,  a  practically  noiseless  operation 
of  the  movement  without  perceptible  wear  on  the 
parts,  is  insured. 


Detailed  views  of  the  new  movement,  showing  the  cam  with  the 

disc  which  holds  the  roller  bearings  in  place, 

and  the  pin  cross  with  bearings  removed 


202  MOTION     PICTURE     PROJECTION 


Power's  Cameragraph  No.  6A 
Showing  film  threaded  through  machine 


MOTION     PICTURE     PROJECTION 


203 


WORKING  OPERATION  OF  POWER'S 
LOOP-SETTER 

The  illustration  shows  a  strip  of  film  forming  the 
lower  loop  around  roller  (A).  When  the  loop  is  lost 
(drawn  taut),  the  roller  is  necessarily  elevated,  thus 
causing  a  slight  rotary  motion  in  cylinder  (B).  A 
diagonal  slot  in  this  cylinder,  in  contact  with  a  pin 
fastened  to  arm  (E),  causes  the  arm  to  move  out- 
ward; but  as  arm  (C)  operates  as  a  lever,  with  its 
fulcrum  at  point  (D),  the  other  end  of  the  arm  at 


Automatic  Loop-Setter 

(E)  moves  inward,  thus  disengaging  pin  (F)  from 
the  driving  pulley  (G).  This  breaks  the  connection 
whereby  motion  is  transmitted  to  take-up  sprocket 
(H),  and  the  sprocket  stops  revolving.  The  loop  re- 


204 


MOTION     PICTURE     PROJECTION 


forms  instantly,  and  roller  (A)  is  forced  back  into 
its  original  position  by  coil  spring  (I).  Pin  (F) 
immediately  re-engages  with  driving  pulley  (G),  and 
the  take-up  sprocket  (H)  starts  to  revolve  again  as 
a  natural  consequence.  The  whole  train  of  opera- 
tion is  automatic — its  results  instantaneous. 


MOTION     PICTURE     PROJECTION  205 


6B   WITH   TYPE  "E"   LAMPHOUSE 


206  MOTION     PICTURE     PROJECTION 


POWERS   TAKE-UP 


MOTION     PICTURE     PROJECTION  207 


POWER'S  6B  TAKE-UP 

The  6B  Take-up  is  simplicity  itself.  It  consists 
primarily  of  two  friction  discs,  which  are  held  in 
contact  by  means  of  a  spring.  One  of  these  discs  is 
faced  with  fibre,  which  assures  an  excellent  frictional 
contact.  The  driving  disc  (a)  is  left  free  to  revolve 
around  Take-up  spindle  (b),  as  an  axis.  The  driven 
disc  (c)  is  fastened  to  spindle  (b).  By  frictional 
contact,  motion  is  transmitted  from  disc  (a)  to  disc 
(c)  and  thus  spindle  (b)  is  caused  to  revolve 
also.  The  take-up  reel  fastens  to  spindle  (b)  at  (d). 
The  reel  is  held  firmly  on  the  spindle  by  means  of 
catch  (e).  When  the  catch  is  in  a  horizontal  posi- 
tion, it  is  in  exact  line  with  spindle  (b),  thus  mak- 
ing it  very  easy  to  put  the  reel  on,  or  take  it  off  the 
spindle.  Spindle  (b)  runs  in  ball  bearings  (f),  which 
eliminate  all  unnecessary  friction  in  operation. 

As  the  film  winds  on  the  reel,  the  steadily  increas- 
ing load  gradually  retards  the  speed  at  which  disc 
(c)  revolves,  and  this  automatically  regulates  the 
revolutions  of  the  Take-up  reel,  so  that  at  every 
moment  the  proper  tension  on  the  film  is  assured. 

The  friction  between  discs  (a)  and  (c)  may  be 
adjusted  by  increasing  or  decreasing  the  tension  on 
spring  (g).  This  may  be  accomplished  by  simply 
giving  a  few  turns  in  either  direction,  to  collar  (h), 
which  is  threaded  on  the  end  of  spindle  (b).  When 
the  desired  tension  has  been  secured,  the  collar  may 
be  locked  in  place  by  means  of  set  screw  (i). 


208  MOTION     PICTURE     PROJECTION 


AUTOMATIC  SHUTTER 

The  shutter  covering  the  aperture  in  gate  of  ma- 
chine and  controlled  by  the  centrifugal  movement.  It 
is  so  arranged  that  the  shutter  will  be  held  up  by 
centrifugal  force  as  long  as  the  machine  is  in  motion, 
but  should  the  machine  stop  for  any  reason  then  the 
shutter  falls  and  cuts  off  the  light  from  film.  It  is 


625 


741 

The  Centrifugal  Movement  with  Cover  Removed 

a  fire  prevention  device.  Should  the  automatic 
shutter  refuse  to  work  and  same  cannot  be  remedied 
by  oiling,  it  will  then  be  necessary  to  take  the  cover 
off  the  centrifugal  movement  Figure  624,  then  exam- 
ine springs  and  shoes  Figure  741,  and  see  if  the  shoe 
track  Y  is  not  scratched. 


MOTION     PICTURE     PROJECTION  209 


MOTOR  TROUBLES  &  REMEDIES 

Sparking  may  be  due  to  overload,  wrong  position 
of  brushes,  broken  coil,  weak  field,  and  to  any  of  the 
causes  named  for  dynamos. 

Sparking 

Symptom.  Intermittent  Sparking.  On  a  varying 
load,  in  which  the  work  comes  on,  at  the  beginning 
or  end  of  each  cycle,  and  then  falls  off  during  the 
remainder  of  the  cycle,  a  motor  often  sparks  just  as 
the  peak  load  comes  on. 

The  cause  is  the  heavy  current  taken  at  the  in- 
stant of  maximum  load,  which  distorts  and  weakens 
the  effective  field  and  shifts  the  neutral  point.  This 
weakening  of  the  field  results  in  a  still  larger  current 
in  the  armature,  aggravating  the  evil. 

Remedy.  Add  a  compounding  coil  on  the  motor 
to  assist  the  shunt,  or  exchange  the  motor  for  a  com- 
pound-wound one,  or  one  with  interpoles. 

Failure  to  Start 

(1)  Symptoms.  Motor  does  not  start.  Little  or 
no  current  passes  on  closing  the  D.P.  switch  and 
pushing  starting  handle  over. 

Probable  Causes.  Brushes  not  down.  Switch  not 
making  contact  in  the  jaws.  Starting  switch  not 
touching  the  contacts.  Fuse  broken.  Controller 
fingers  not  touching  contact  plates.  Break  in  series 
coil  (if  a  series  motor).  Terminal  loose.  No  cur- 
rent on  mains. 


210  MOTION     PICTURE     PROJECTION 

If  the  no-volt  release  coil  excites,  or  if  a  long  arc 
is  observed  on  breaking  circuit,  it  indicates  that  the 
shunt  field  gets  its  current  and  the  probable  cause 
of  the  failure  to  start  is  that  the  shunt  is  connected 
in  series  with  the  armature  owing  to  two  of  the  leads 
from  the  starter  being  reserved. 

Remedy.  Trace  out  the  connections  or  use  test- 
ing set. 

Failure  to  start 

(2)  Symptom.  Motor  does  not  start,  but  takes 
excessive  current.  Fuse  or  overload  cut-out  acts. 

Cause.  It  is  assumed  the  motor  is  not  overloaded ; 
this  can  be  tested  by  taking  load  off  and  trying  to 
start  motor  light.  If  a  shunt  motor  there  may  be 
a  short  circuit  in  connecting  cables  or  in  field  coil; 
or  in  armature ;  or  a  break  in  field  coil. 

Remedy  for  broken  field.  If  field  excites  when 
brushes  are  up,  but  not  when  they  are  down,  the 
symptoms  point  to  a  short  circuit  in  or  across  arma- 
ture, or  brushes. 

Examine  brushes  for  short  circuit  to  frame,  for 
copper  dust,  oil,  or  broken  down  insulation. 

Then  disconnect  armature  and  excite  field.  Move 
armature  round  quickly  by  hand.  A  drag  will  be  felt 
as  the  short  circuited  coils  pass  the  poles.  If  the 
armature  can  be  driven  at  a  fair  speed  by  belt,  with 
the  field  excited,  the  short-circuited  coils  will  warm 
up  and  can  probably  be  located  in  this  way. 

If  the  above  symptoms  occur  with  a  series-wound 
motor,  the  cause  may  be  a  short  in  the  field  or  arm- 
ature, but  not  a  break. 


MOTION     PICTURE     PROJECTION  211 

A  fairly  common  cause  is  incorrect  connecting  up. 

Another  cause,  particularly  with  machines  that 
have  been  dismantled,  is  incorrect  polarity  of  the 
field  coils.  Thus  if  the  coils  are  connected  up  so  that 
they  are  all  of  the  same  polarity,  the  effect  is  the 
same  as  with  a  broken  field  wire  as  the  field  is  com- 
pletely neutralized.  If  only  one  of  the  field  coils  is 
reversed  in  a  four-pole  motor,  the  motor  would  prob- 
ably not  start  and  would  in  any  case  take  an  exces- 
sive current. 

Remedy.     Test  the  coils  for  polarity. 

Incorrect  Speed 

A  certain  amount  of  speed  adjustment  may  be  ob- 
tained by  altering  the  position  of  the  brushes.  Mov- 
ing the  brushes  backwards  from  the  neutral  point  has 
the  effect  of  increasing  the  speed,  whilst  moving  them 
forward  reduces  the  speed. 

Excessive  Speed 

Symptom.  Motor  starts,  then  speed  gradually  in- 
creases till  motor  runs  at  very  excessive  speed.  This 
only  occurs  when  a  motor  starts  light  or  on  a  very 
light  load  such  as  a  loose  pulley. 

Cause.  If  shunt  or  compound  motor.  Shunt  coil 
connected  in  series  with  armature  instead  of  in 
parallel. 

On  first  switching  on,  the  magnets  excite,  as  the 
armature  is  stationary  and  allows  the  full  shunt 
current  to  pass  the  coils.  As  the  armature  speeds 
up  it  puts  a  back  E.M.F.  in  the  circuit,  gradually 
reducing  the  current  passing  and  thus  weakening  the 


212  MOTION     PICTURE     PROJECTION 

field.     The  faster  the  armature  goes  the  weaker  the 
field  becomes.     A  short  circuit  in  the  shunt  might 
produce  same  result  if  motor  starts  absolutely  light. 
Remedy.    Connect  up  the  shunt. 

Fuse  Blows 

Symptom.  Motor  starts  and  runs  up  to  its  proper 
speed,  but  fuse  or  overload  acts  on  putting  load  on. 

Cause.  This  is  a  sign  of  overload.  Probably  belts 
too  tight,  bearings  tight  or  dry. 

If  the  fuse  blows  whilst  starting  up  there  may  be 
a  ground  on  the  motor.  This  should  be  tested.  If 
the  starter  is  provided  with  shunt  sector  the  fuse 
may  blow  whilst  starting  up,  owing  to  a  bad  contact 
to  this  sector,  due  either  to  dirt  or  to  a  hollow  place 
in  the  metal. 

In  the  case  of  a  compound-wound  motor  a  cross 
connection  or  leakage  between  the  series  and  shunt 
windings  will  cause  the  fuse  to  blow  if  the  cross  is 
in  a  position  that  the  shunt  is  practically  short  cir- 
cuited by  the  series. 

Starter  Overheats 

Symptom.  Motor  starting  against  load  takes  ex- 
cessive current.  Last  few  coils  of  resistance  overheat 
(probably  smoke  or  get  red  hot).  Fuse  or  overload 
acts,  or  motor  sparks. 

Cause.    Overload ;  or  starter  too  small. 

When  a  motor  starts  against  a  load  having  con- 
siderable inertia,  such  as  heavy  line  shaft  with  several 
large  pulleys  and  tight  belts,  or  against  a  heavily 
fly-wheeled  machine,  time  must  be  given  for  it  to  get 


MOTION     PICTURE     PROJECTION  213 

up  speed.  If  the  starter  is  moved  over  the  contacts 
more  quickly  than  the  motor  can  accelerate,  an  ex- 
cessive current  will  pass,  causing  the  motor  to  spark. 
The  starter  must  be  put  on  more  slowly  and  this  will 
cause  it  to  heat  up  unless  it  has  been  liberally  rated. 

Remedy.  Exchange  starter  for  one  having  more 
margin,  that  is  one  which  permits  of  starting  up 
slower.  This  does  not  mean  a  starter  for  a  larger 
H.P. 

Starts  Suddenly 

Symptom.  Motor  does  not  start  nor  take  current 
till  most  of  resistance  is  cut  out,  then  takes  rush  of 
current  and  starts  suddenly. 

Cause.  A  break  in  the  starting  resistance. 
Temporary  Remedy.  Connect  the  contacts  where 
break  occurs,  until  resistance  can  be  repaired. 

Wrong  Direction 

Symptom.     Motor  runs  in  wrong  direction. 
Remedy.     Reverse  armature  or  field  connections, 
whichever  is  the  easier,  but  not  both. 

In  a  compound-wound  machine  both  the  shunt  and 
series  coil  must  be  reversed  if  the  field  be  reversed; 
but  if  the  machine  be  provided  with  interpoles  these 
must  be  treated  as  part  of  the  armature  and  must 
therefore  not  be  reversed  when  the  field  is  reversed. 

Motor  Reverses 

Symptom.  Motor  starts  up  and  runs  correctly 
on  light  load.  On  an  overload,  or  reduced  voltage, 
motor  reverses  and  runs  backwards. 

Cause.  This  applies  to  a  compound-wound  motor, 
with  the  series  or  compound  coil  connected  up  in 
opposition  to  the  shunt  coil. 


214  MOTION     PICTURE     PROJECTION 

Remedy.     Reverse  the  series  coil. 

Flashing 

Symptom.  Severe  sparking  or  flashing  apparently 
all  round  the  commutator ;  over-heating  of  the  arma- 
ture and  burning  of  the  insulation  between  a  couple 
of  the  segments. 

Cause.  The  cause  of  the  above  is  a  broken  wire 
in  the  armature  winding. 

Remedy.  If  the  broken  end  cannot  be  located  and 
repaired  easily,  the  armature  must  be  stripped  until 
the  break  is  found  and  the  section  re-wound.  A 
temporary  repair  can  sometimes  be  made  sufficiently 
to  enable  the  motor  to  continue  working,  by  joining 
across  the  two  segments  on  each  side  of  the  burnt 
mica  with  a  short  piece  of  copper  wire,  the  wire 
being  laid  on  the  ears  of  the  commutator  and  sweated 
in  with  a  soldering  iron.  This  practically  converts 
two  segments  into  one,  and  the  motor  will  run  in  this 
way  quite  satisfactorily.  If  the  commutator  lugs 
are  not  readily  accessible,  a  copper  pin  may  be  driven 
hard  down  between  the  two  segments  in  a  part  not 
under  the  brushes. 

Flashing  Over 

Symptom.  On  an  overload  and  sometimes  on  a 
normal  load  a  motor  will  flash  from  the  brushes  to 
a  part  of  the  commutator  or  to  the  rocker,  and  blow 
the  fuses.  This  is  more  liable  to  happen  with  a 
weak  field. 

Cause  and  Remedy.  The  cause  is  that  the  motor 
has  too  much  forward  lead,  and  the  brushes  should 
be  moved  back  a  little. 


MOTION     PICTURE     PROJECTION  215 


ROBIN  SIGNAL  TELEGRAPH  SYSTEM 

The  Robin  Signal  Telegraph  system  is  an  audible 
and  visual  signal  system  which  provides  a  positive 
means  of  transmitting  co-ordinated  signals  between 
the  operating  room,  stage,  and  orchestra  pit  with 
certainty  and  dispatch. 

The  system  consists  of  a  master  station  which 
is  placed  on  the  stage  director's  stand  or  on  the 
orchestra  leader's  desk,  and  is  connected  with  the 
orchestra  pit  and  meters  in  the  booth. 

The  signal  dispatch  station  consists  of  a  panel 
board  and  a  radial  switch  with  several  contacts.  In 
operation  the  switch  can  be  set  at  any  point  desired 
as  far  in  advance  as  desired  and  when  the  button 
is  pushed,  will  call  the  operator's  attention  to  the 
signal. 


Robin  Signal  Telegraph  With  Eight  Synchronized  Meters  as 
Installed  in  New  York  Capitol 


216  MOTION     PICTURE     PROJECTION 

At  the  master  station  is  provided  an  instrument 
similar  to  those  installed  in  the  booth,  and  which 
serves  the  purpose  of  a  master  meter  and  conveys 
to  the  director  or  leader  sending  the  signal,  means 
of  ascertaining  the  correct  working  of  the  system 
and  also  as  a  telltale  of  whether  the  instruments  in 
the  booth  are  registering  the  correct  signals.  If 
the  master  meter  does  not  function,  none  of  the 
others  will  operate. 

The  meters  in  the  booth  are  generally  placed  one 
under  each  look-out  hole,  that  the  operator,  no  mat- 


Robin  Signal  Telegraph  Despatch  Station 


MOTION     PICTURE     PROJECTION  217 

ter  where  located,  receives  the  same  signal.  Each 
meter  has  a  plate  provided  with  a  scale  on  which 
is  engraved,  "ready,  go,  stop,  slower,  faster,  see 
programe,  light,  focus,  and  frame." 

This  instrument  supersedes  the  use  of  the  tele- 
phone and  the  ordinary  and  troublesome  return  call 
buzzer  system. 

In  actual  operation  instead  of  the  leader  or  stage 
director  telephoning  to  the  operator  and  calling  him 
away  from  his  projection  machines  he  throws  the 
switch  over  on  the  signal  and  presses  the  button  and 
the  operator,  without  leaving  his  position  receives 
both  an  audible  and  visual  signal. 

At  the  rear  of  the  control  board  on  the  master 
station  is  mounted  a  capirating  rheostat  with  re- 
sistance to  correspond  with  the  various  points  on  the 
scale.  There  is  also  provided  an  adjusting  rheostat 
to  compensate  any  drop  in  voltage  or  differences  be- 
tween the  points  of  the  scale 

Wire  required  from  the  booth  to  the  orchester  pit 
is  five  No.  16  B  &  S  gauge  wires,  two  for  the  signal 
and  three  for  the  return  call. 

The  source  of  energy  is  dry  batteries  and  one  set 
of  cells,  this  being  sufficient  for  an  entire  year. 


218 


MOTION     PICTURE     PROJECTION 


CARBONS 

There  are  two  classes  of  carbons  generally  used  in 
arc  lamps,  solid  and  cored;  they  are  composed  of 
coke,  tar,  or  the  graphite  deposited  in  the  inside  of 
retorts  used  for  manufacturing  illuminating  gas. 
With  solid  carbons  the  crater  travels  around  the 
ends  of  the  carbons,  the  current  always  tending  to 
take  the  path  of  least  resistance ;  with  cored  carbons, 
which  are  solid  except  for  an  inner  core  of  softer 
carbon,  the  travel  of  the  crater  is  reduced  and  the 
distribution  of  light  more  steady.  The  effect  of  the 
core  is  to  confine  the  current  to  the  center  of  the 
rod,  and  consequently  the  arc,  due  to  the  core  hav- 
ing a  higher  conductivity  than  the  surrounding  ma- 
terial. With  cored  carbons  the  voltage  across  the 
arc  is  reduced. 


-JSL 


\J 


t 

(     / 
//     / 

/    /       - 


f\ 


Right  and  wrong  way  to  set  D.  C.  arc.     I.  Lower  carbon 

not  far  enough  forward.     II.  Correct  setting. 

III.  Lower  carbon  too  far  advanced 


MOTION    PICTURE     PROJECTION  219 

In  an  alternating  current  arc  the  crater  alter- 
nates from  one  carbon  to  the  other  with  each  reversal 
of  current,  so  that  both  carbons  are  consumed  equal- 
ly when  the  rods  are  horizontal.  When  vertical,  the 
upper  carbon  will  be  consumed  about  8  per  cent, 
faster,  owing  to  the  action  of  the  ascending  currents 
of  heated  air. 

The  Projection  Arc 

Since  the  experience  of  some  operators  has  been 
limited  to  projection  with  the  alternating-current 
arc,  the  following  suggestions  are  offered  on  projec- 
tion with  the  direct-current  arc : 

The  direct-current  arc  should  be  approxi- 
mately 5/16  to  %  inch  long  or  about  twice  the 
length  of  the  alternating-current  arc.  Too  short 
an.  arc  will  not  give  a  satisfactory  light,  the  trouble 
being  not  in  the  machine  but  in  the  carbon  setting. 

Use  only  the  best  projection  carbons.  Pro- 
jection'carbons  vary  greatly  in  quality  and  good 
results  cannot  be  obtained  from  poor  carbons.  In- 
ferior carbons  are  particularly  liable  to  give  trouble 
on  arc  currents  of  50  amperes  and  above.  Good 
carbons  will  be  uniform  in  diameter,  straight,  free 
from  cracks  running  around  the  circumference,  and 
uniform  in  density  throughout.  The  core  will  be 
true  to  the  center  of  the  carbon  and  will  not  drop 
out  while  burning.  A  hard  spot  in  the  carbons  will 
cause  the  arc  to  jump  and  sputter,  while  a  soft  spot 
will  cause  it  to  flame  or  needle  and  burn  away  very 
rapidly.  The  main  point  in  setting  the  carbons  is 
to  get  a  crater  to  form  good  size  and  facing  the 
center  of  the  condenser  lens  as  nearly  as  possible. 


220 


MOTION     PICTURE     PROJECTION 


Take  care  to  have  the  carbons  in  perfect 
alignment  sidewise  and  a  long  enough  arc  that  the 
lower  carbon  does  not  "mushroom."  Pull  the  upper 
carbon  back  slightly  which  will  face  the  crater 
forward  toward  the  condenser.  If  the  upper  carbon 
is  not  back  far  enough  the  crater  will  point  down- 
ward and  not  toward  the  condenser.  If  too  far 
back,  a  long  "skirt"  will  form  on  the  back  edge  of 
the  upper  carbon  which  will  give  an  unsteady  light 
and  may  break  off  in  feeding,  giving  a  very  poor 
light  until  a  new  crater  can  be  formed. 

Do  not  try  to  decide  upon  the  merits  of  carbons 
by  burning  just  one  carbon  of  a  kind  in  just  one 


"Columbia." 
UPPER  CARBON 


Correct    Setting 


FRONT 


MOTION     PICTURE     PROJECTION  221 

way;  try  out  a  carbon  setting  at  least  one  whole 
day  to  see  if  results  cannot  be  improved. 

There  has  come  into  use  recently  a  small  diameter 
metal  coated  hard  core  negative  carbon  which  has 
been  found  in  many  cases  to  improve  the  operation 
of  the  arc  by  holding  it  quiet  and  steady. 

CARBON  COMBINATIONS  FOR  NATIONAL 
CARBONS 

DIRECT  CURRENT 
Current  Size  Carbons 

For  25  to  60  Amps.  (  5/8  x  12  inch  Cored  Upper 

D.  C.  use  (  5/16  x  6  inch  Metal  Coated  Solid  Lower 

For  50  to  65  Amps,  f  3/4  x  12  inch  Cored  Upper 

D.  C.  use  {  11/32x6  inch  Metal  Coated  Solid  Lower 

For  65  to  70  Amps.  C  7/8  x  1C  inch  Cored  Upper 

D.  C.  use  I  11/32x6  inch  Metal  Coated  Solid  Lower 

For  70  to  85  Amps.  C  7/8  x  12  inch  Cored  Upper 

D.  C.  use  |  3/8  x  6  inch  Metal  Coated  Solid  Lower 

For  85  to  100  Amps,  f  1  x  12  inch  Cored  Upper 

D.  C.  use  (7/16x6  inch  Metal  Coated  Cored  Lower 

ALTERNATING  CURRENT 
Amperes  Carbon  Diameter 

40  or  less  than     60  5/8  inch  Combination 

60  or  less  than     75  3/4  inch  Combination 

75  or  less  than  100  7/8  inch  Combination 

Projector  Carbon  Manufacturing  Process 

In  the  manufacture  of  high-grade  projector  car- 
bons it  is  necessary  to  use  an  especially  prepared 
carbon  flour.  The  flour  is  carefully  mixed  with  the 
necessary  binding  material  and  forced  by  hydraulic 
presses  under  high  pressure  into  the  desired  shape. 


220 


MOTION     PICTURE     PROJECTION 


Take  care  to  have  the  carbons  in  perfect 
alignment  sidewise  and  a  long  enough  arc  that  the 
lower  carbon  does  not  "mushroom."  Pull  the  upper 
carbon  back  slightly  which  will  face  the  crater 
forward  toward  the  condenser.  If  the  upper  carbon 
is  not  back  far  enough  the  crater  will  point  down- 
ward and  not  toward  the  condenser.  If  too  far 
back,  a  long  "skirt"  will  form  on  the  back  edge  of 
the  upper  carbon  which  will  give  an  unsteady  light 
and  may  break  off  in  feeding,  giving  a  very  poor 
light  until  a  new  crater  can  be  formed. 

Do  not  try  to  decide  upon  the  merits  of  carbons 
by  burning  just  one  carbon  of  a  kind  in  just  one 


> J 


ColuYnbx  a." 
UPPtP  CARBON 


Correct    Setting 


MOTION     PICTURE     PROJECTION  221 

way;  try  out  a  carbon  setting  at  least  one  whole 
day  to  see  if  results  cannot  be  improved. 

There  has  come  into  use  recently  a  small  diameter 
metal  coated  hard  core  negative  carbon  which  has 
been  found  in  many  cases  to  improve  the  operation 
of  the  arc  by  holding  it  quiet  and  steady. 

CARBON  COMBINATIONS  FOR  NATIONAL 
CARBONS 

DIRECT  CURRENT 

Current  Size  Carbons 

For  25  to  60  Amps.  J  5/8  x  12  inch  Cored  Upper 

D.  C.  use  [5/16x6  inch  Metal  Coated  Solid  Lower 

For  50  to  65  Amps.  C  3/4  x  12  inch  Cored  Upper 

D.  C.  use  ( 11/32  x  6  inch  Metal  Coated  Solid  Lower 

For  65  to  70  Amps,  f  7/8  x  10  inch  Cored  Upper 

D.  C.  use  I  11/32  x  6  inch  Metal  Coated  Solid  Lower 

For  70  to  85  Amps,  f  7/8  x  12  inch  Cored  Upper 

D.  C.  use  (3/8x6  inch  Metal  Coated  Solid  Lower 

For  85  to  100  Amps,  ( 1  x  12  inch  Cored  Upper 

D.  C.  use  I  7/16  x  6  inch  Metal  Coated  Cored  Lower 

ALTERNATING  CURRENT 

Amperes  Carbon  Diameter 

40  or  less  than     60  5/8  inch  Combination 

60  or  less  than     75  3/4  inch  Combination 

75  or  less  than  100  7/8  inch  Combination 

Projector  Carbon  Manufacturing  Process 

In  the  manufacture  of  high-grade  projector  car- 
bons it  is  necessary  to  use  an  especially  prepared 
carbon  flour.  The  flour  is  carefully  mixed  with  the 
necessary  binding  material  and  forced  by  hydraulic 
presses  under  high  pressure  into  the  desired  shape. 


222  MOTION     PICTURE     PROJECTION 

If  a  cored  carbon  is  wanted,  a  steel  needle  is  suspend- 
ed in  the  center  of  the  die.  The  forced  carbons  are 
then  placed  on  racks  to  cool  and  when  sufficiently 
cool  they  are  cut  in  the  proper  length  for  baking. 
To  insure  absolute  straightness,  correct  size  and  per- 
fect stock  before  baking,  the  cooled  carbons  are 
thoroughly  inspected  before  being  turned  over  to  the 
baking  department. 

In  the  furnaces,  the  carbons  are  subjected  to  the 
temperature  necessary  to  produce  a  uniform  carbon 
of  certain  definite  prescribed  qualities.  After  the 
bake  is  completed,  the  furnace  is  sampled  and  the 
carbons  examined  by  the  testing  department  before 
being  sent  along  for  finishing.  These  tests  are  even 
more  severe  than  those  to  which  a  projector  carbon 
is  subjected  by  the  user. 

Upon  receiving  the  testing  department's  O.K.,  the 
carbons  are  sorted  for  straightness  and  examined  for 
imperfections,  and  if  they  are  hollow  shells,  made 
ready  for  coring.  Every  precaution  is  taken  in  the 
coring  department,  where  the  hollow  shells  are  filled 
to  see  that  the  core  material  fills  the  entire  length 
of  the  carbon.  The  composition  of  the  coring  ma- 
terial is  of  considerable  importance  as  it  determines 
largely  the  burning  quality  and  color  of  the  arc. 
After  coring,  the  carbons  are  dried,  finished,  pointed, 
inspected  and  placed  in  the  shipping  stock. 

The  Carbon  Arc 

In  the  direct  current  arc,  the  crater  of  the  positive 
carbon  forms  the  principal  light  source.  The  posi- 
tive crater  is  of  relatively  large  area,  while  the  nega- 
tive spot  is  small  and  is  not  usually  considered  as  a 


MOTION    PICTURE     PROJECTION  223 

light  source.  While  95%  of  the  light  emitted  by  the 
arc  comes  from  the  positive  crater,  the  character- 
istics of  the  negative  carbon  are  of  vital  importance 
in  securing  steadiness  of  operation.  In  operation, 


1 


Fig.    1  pig<    2 

the  positive  crater  is  set  so  as  to  face  the  axis  of 
the  optical  system.  In  setting  the  carbons  in  this 
position,  care  must  be  taken  to  reduce  to  a  minimum 
the  shading  of  the  crater  by  the  negative  carbon. 
In  this  respect,  the  direct  current  arc  is  superior 
to  the  alternating  current  arc.  A  direct  current  arc 
is  longer  and  therefore  gives  less  shading  of  the 
crater.  The  greatest  advantage  of  the  direct  cur- 
rent arc  is  the  fact  that  the  current  travels  only 
in  one  direction  and  therefore  the  positive  crater  re- 
ceives electrical  energy  continously  and  consequently 
maintains  a  higher  temperature. 

As  was  stated  above  the  characteristics  of  the 
lower  carbon  on  direct  current  are  of  greatest  im- 
portance in  securing  steadiness  of  operation.  The 
size  of  the  upper  carbon  is  determined  by  the  power 


224  MOTION     PICTURE     PROJECTION 

imputed  to  the  arc.  If  the  positive  is  too  small  the 
current  will  overlap  the  end  of  the  carbon  and  the 
arc  will  be  noisy  and  unsteady.  If  too  large,  the 
crater  covers  the  end  of  the  carbon  and  the  arc 
again  will  be  unsteady,  because  the  average  temper- 
ature at  the  tip  is  lower.  With  the  negative  car- 
bon, the  carrying  capacity  is  the  important  factor 
since  the  size  of  the  negative  carbon  required  by  the 
negative  spot  is  small.  A  small  carbon  keeps  the  arc 
steady  and  also  eliminates  the  shadow  due  to  the 
shading  of  the  crater  by  the  negative  carbon  itself. 
This  problem  has  been  solved  by  plating  the  solid 
negative  over  its  entire  length  with  a  series  of  metal- 
lic coats  forming  a  shell  of  metal  of  low  electrical 
resistance  around  the  carbon.  This  metallic  coating 
volatizes  in  the  heat  of  the  arc  and  thus  prevents 
the  spattering  of  the  rear  condenser  lens  with  the 
heavy  metal  beads  formed  with  the  old  style  metal 
coat.  The  coating  carries  the  major  part  of  the 
current  and  makes  possible  the  use  of  a  small  nega- 
tive with  the  high  currents  required  by  long  throws 
and  dense  films. 

The  direct  current  arc  is  inherently  stable  and  the 
range  of  arc  voltage  can  be  made  whatever  the  pro- 
jectionists desire,  but  there  is  one  fact  to  be  borne 
in  mind  that,  for  each  given  current  value  there  is 
a  definite  arc  voltage  at  which  the  arc  operates  at 
maximum  efficiency.  With  a  constant  current  value, 
gradually  shortening  the  arc  length,  will  finally  pro- 
duce an  unstable  arc;  just  previous  to  that  point  is 
the  limiting  voltage  for  the  current  chosen.  Or, 
otherwise,  a  given  current  requires  a  certain  arc 
length  of  voltage.  To  increase  the  current  and  not 
change  the  arc  length,  is  equivalent  to  shortening  the 


MOTION     PICTURE     PROJECTION 


5225 


arc  in  the  first  case  and  the  arc  becomes  noisy.  For 
this  reason  increasing  voltages  are  required  for  in- 
creasing currents. 

When  using  small  diameter  solid  metal  coated 
negatives  on  direct  current  we  start  at  52  volts  for 
30  amperes  and  increasing  by  2  volts  for  each  in- 
crease of  10  amperes,  reaching  62  for  the  arc  voltage 
at  100  amperes,  a  saving  of  0.7  kw.  or  10  percent, 
in  arc  wattage,  than  in  case  where  the  old  style  large 
diameter  cored  negatives  are  used,  starting  at  55  arc 


Bev«kd    tpd 


COttDfcftdERS 


volts  for  30  amperes  direct  current,  and  increasing 
voltage  and  current  in  same  proportion  as  recom- 
mended in  former  case. 

In  the  past  when  using  cored  negative  carbons  the 
basis  for  choice  of  the  negative  was  a  ratio  of  1  for 
the  negative  diameter,  to  1.65  for  the  positive  dia- 
meter, or  a  cross-sectional  ratio  of  1.2. 


226  MOTION     PICTURE     PROJECTION 

Under  the  table  of  Carbon  Combinations  for  direct 
current  projection,  the  new  developed  solid  small 
diameter  metal  coated  negative  calls  for  a  cross-sec- 
tional ratio  of  1.4,  the  negative  having  y\  area  of 
the  positive. 

What  determines  the  size  of  a  carbon  for  given 
service  is  the  ability  to  stand  up  under  it  but  the 
limiting  factor  differs  in  A.  C.  and  in  D.  C. 

On  direct  current  the  limiting  factor  is  the  crater. 
Since  the  temperature  of  a  carbon  arc  is  constant 
just  as  is  the  temperature  of  boiling  water — be  there 
a  teaspoonful  or  a  barrel  full — so,  by  putting  into 
the  carbon  more  current,  we  merely  increase  the  num- 
ber of  the  hot,  light-giving  areas  until  finally  the  tip 
of  the  carbon  or  crater  can  no  longer  accommodate 
an  increase  and  then  no  further  increase  of  light  is 
possible  for  that  carbon.  The  body  of  the  carbon  is 
as  yet  unaffected  by  the  current  but  the  crater  can 
no  longer  take  care  of  further  increases.  This  is 
the  limiting  factor  and  so  we  take  the  next  larger 
sizes. 

On  alternating  current  the  crater  is  but  half  the 
size  of  the  crater  formation  on  direct  current,  owing 
to  the  fact  that  the  energy'  is  divided  equally  between 
the  upper  and  lower  carbon;  therefore,  we  can  go 
still  higher  in  current  density  on  A.  C.  without  reach- 
ing a  crater  limit  but  we  now  find  that  the  carbon 
body  cannot  carry  an  unlimited  amount  of  current 
without  glowing  and  oxidizing  away  sharply,  so  we 
are  limited  on  A.  C.  to  the  physical  characteristics 
of  the  carbon.  Using  the  old  style  alternating  cur- 
rent carbon,  a  short  air  gap  gives  a  hissing  and  sput- 
tering arc  which  is  very  unstable.  By  using  cored 
carbons,  the  cores  of  which  are  impregnated  with 


MOTION     PICTURE     PROJECTION 


227 


carefully  prepared  chemicals,  an  absolutely  silent 
and  steady  alternating  current  arc  can  be  obtained. 
By  using  the  proper  chemicals  a  light  source  of  high 
intensity  is  obtained  which  is  far  above  that  of  the 
old  cored  carbons. 

This  change  in  the  construction  of  carbons  for  use 
with  alternating  current  projection  is  one  that  has 
come  to  the  front  in  the  last  year  and  has  met  with 


A  Mushroom  Arc 

marvelous  success.  It  has  brought  the  alternating 
current  arc  in  close  competition  with  the  direct  cur- 
rent arc  and  it  has  allowed  many  houses  who  had 
seriously  considered  adopting  other  sources  of  illu- 
mination to  continue  with  the  alternating  current 
arc  without  necessitating  a  single  change  in  or  about 
the  lamp  house  or  in  the  wiring.  The  mere  substi- 
tution of  these  new  carbons  for  the  old  style  alter- 
nating current  carbons  makes  the  alternating  current 
arc  a  very  desirable  and  economical  light  source  for 
projection. 


228  MOTION     PICTURE     PROJECTION 

In  addition  to  fulfilling  the  general  requirements, 
the  carbon  arc  has  other  characteristics  which  make 
it  adaptable  for  motion-picture  work.  These  char- 
acteristics are:  Color  of  light;  Reliability;  Flexi- 
bility ;  Steadiness. 

Color  of  Light:  Until  recently,  the  color  of  the 
light  used  for  the  projection  of  the  high-class  film 
was  a  source  of  much  annoyance.  It  is  obvious  that 
where  the  picture  is  taken  in  the  open  and  in  bright 
daylight,  the  effect  upon  the  screen  would  be  inferior 
unless  the  projection  light  source  approached  that 
of  daylight  in  color  value.  The  light  of  the  direct 
current  arc  is  the  nearest  approach  in  color  value  to 
daylight  of  any  of  the  known  illuminants  that  could 
be  used  for  motion-picture  projection.  The  light  is 
a  pure  white  of  high  intensity.  The  light  of  the  al- 
ternating current  arc  using  the  modern  high-grade 
projector  carbon  approaches  that  of  the  direct  cur- 
rent arc  both  in  color  value  and  intensity.  A  pure 
white  light  is  beyond  doubt  the  proper  kind  of  light 
to  use  for  projection  since  it  brings  out  the  high 
lights  and  shadows  and  will  project  upon  the  screen 
a  picture  that  will  please  the  most  critical  audience. 

Reliability:  The  arc  in  the  hands  of  an  efficient 
projectionist,  is  a  very  reliable  light  source.  It  is 
not  easily  affected  by  fluctuations  in  line  voltage  and 
therefore  will  give  an  even  screen  illumination  where 
other  illuminants  will  fail.  Carbons  have  a  definite 
length  of  life  and  therefore  the  projectionist  can 
guard  against  the  failure  of  light  in  the  middle  of 
a  reel  of  film. 

Flexibility :  The  carbon  arc  gives  a  steady,  flexible 
light,  variable  at  the  will  of  the  operator  according 
to  the  density  of  the  film.  No  two  films  are  alike  and 


MOTION     PICTURE     PROJECTION 


229 


no  two  parts  of  the  same  film  are  of  the  same  density 
and  consequently  to  give  a  true  artistic  presentation 
of  any  picture  you  must  have  a  flexible  light  source. 

Steadiness :  Both  the  direct  and  alternating  cur- 
rent arcs  are  giving  absolutely  steady  illumination. 
The  traveling  of  the  arc  and  negative  shadows  have 
been  eliminated  in  arc  projection. 

In  conclusion,  emphasis  should  be  placed  upon  the 
use  of  proper  carbon  combinations.  The  carbon 
manufacturer  specifies  a  definite  diameter  of  carbon 
for  a  definite  current  requirement  and  any  deviation 
from  this  will  result  in  poor  projection.  If  the 
projectionist  is  without  positive  knowledge  of  the 
amount  of  power  he  is  using  he  can  obtain  this  by 
means  of  a  voltmeter  and  ammeter.  Standard  in- 
struments for  this  purpose  can  generally  be  obtained 
from  the  local  power  plants. 


Showing  effect  of  arc  being  connected  upside  down 


23d  MOTION     PICTURE     PROJECTION 


THE    SPEER   CARBON 

Speer  Projector  Carbons  have  a  texture  designed 
to  withstand  high  current  densities  and  insure  long 
life,  but  soft  enough  to  give  a  pleasing,  steady,  white 
light  of  great  intensity.  In  order  to  meet  the  de- 
mand for  service  of  the  highest  class,  three  types  are 
offered  the  trade.  The  Directo  Carbon  is  made  es- 
pecially for  D.  C.  positives,  but  may  be  used  as  D.  C. 
negatives.  It  is  of  the  soft  cored  type  and  is  dis- 
tinguished by  .the  perfect  flush  crater  developed. 
The  Hold-Ark  Carbon,  of  the  hard  cored  type,  is 
made  for  D.  C.  negative  work  only,  is  double  electro- 
plated and  is  extensively  used  by  projectionists  who 
desire  a  noiseless,  steady,  white  light.  The  Alterno 
combination  sets  are  the  highest  development  of  car- 
bons for  A.  C.  service  and  produce  a  noiseless  white 
arc.  They  are  furnished  in  packages  containing  25 
12"  carbons  and  50  6"  carbons.  The  12"  carbon 
marked  with  a  yellow  line  must  be  used  only  as  the 
upper  and  the  6"  carbon  marked  with  a  white  line 
must  be  used  only  as  a  lower. 

The  best  screen  results  are  obtained  with  the  fol- 
lowing sizes: 

For  D.  C.  Service: 

25  to  50  amperes 5/8x12"  Directo  and  5/16"   Hold-Ark 

50  to  70         "        3/4  x  12"         "  "    11/32" 

70  to  85         "        7/8  x  12"         "  "        3/8" 

85  to  100       "        1  x  12"         "  "      7/16" 

For  A.  C.  Service: 

85  to  55  amperes 5/8"  Alterno  Combination 

55  to  70        "        3/4" 

70  to  85         "        7/8" 


MOTION     PICTURE     PROJECTION  231 

Speer 
Projector  Carbons 

DIREGTO— Positives  for  Direct  Current 

HOLD-ARK— Negatives  for  Direct 
Current 

ALT  ERNO— White  Light -Noiseless  Sets 
for  Alternating  Current 


Cored,  Solid  and  Metal-Coated  Carbons, 

Searchlight  Carbons,White  Flame  Carbons 

for    Studio   Work,   Photo   Engraving   and 

Spotlight  Carbons. 


Manufactured  By 

SPEER  CARBON  COMPANY 

ST.    MARYS,    PA.,    U.S.A. 


232  MOTION     PICTURE     PROJECTION 

THE  ELECTRIC  ARC 

When  a  current,  under  a  pressure,  is  passed 
through  two  carbon  rods,  with  their  ends  first 
in  contact  and  afterward  gradually  separated  a 
short  distance,  a  brilliant  arc  of  flame  called  the 
electric  arc,  is  established  between  them.  This  arc 
is  composed  of  carbon  vapor,  that  is,  the  high  tem- 
perature caused  by  the  passage  of  the  current 
through  the  resistance  of  the  contact  surfaces  causes 
the  carbon  to  practically  boil  and  the  vapor  thus 
arising,  being  a  much  better  conductor  than  the  air, 
conducts  the  current  across  the  gap  from  one  carbon 
tip  to  the  other.  This  volatilization  occurs  chiefly 
at  the  end  of  the  positive  carbon  terminal  where  the 
current  enters  the  arc,  and  this  point  is  also  the  seat 
of  the  highest  temperature  and  maximum  light- 
emitting  power.  As  the  arc  is  maintained  across  the 
gap,  disintegration  of  the  carbon  takes  place,  the 
carbons  waste  away,  and  a  cup-shaped  depression, 
termed  the  crater,  is  formed  in  the  positive  carbon, 
while  the  tip  of  the  negative  carbon  has  a  conical 
form.  The  negative  carbon  being  at  a  lower  tem- 
perature than  the  positive,  the  vapor  of  the  boiling 
carbon  condenses  upon  its  surface  as  pure  graphite. 
Both  carbons  waste  away,  but  the  consumption  of 
the  positive  carbon  is  about  twice  as  rapid  as  that  of 
the  negative,  since  it  is  this  carbon  from  which  most 
of  the  vapor  comes  and  part  of  which  is  re-deposited 
as  graphite  on  the  negative  cone-tipped  carbon. 

The  light  emitted  by  any  heated  body  increases 
with  its  temperature.  The  temperature  of  the  car- 
bon in  the  crater,  when  in  a  state  of  ebullition,  is 
about  3500°  C.,  this  being  the  hottest  portion  of 


MOTION     PICTURE     PROJECTION  233 

the  arc,  and  consequently  the  point  from  which  the 
most  light  is  emitted.  About  12  per  cent  of  the 
energy  supplied  to  an  electric  arc  appears  as  light, 
the  balance  being  represented  by  the  heat  evolved. 
About  85  per  cent  of  the  light  emitted  from  an  arc 
lamp  is  reflected  from  the  crater,  the  maximum  il- 
lumination being  in  a  zone  surrounding  the  lamp  at 
an  angle  of  about  40°  to  the  horizontal. 

When  the  arc  is  "struck"  by  bringing  the  carbon 
electrodes  together,  and  the.n,  separating  them  for  a 
short  distance,  the  arc  possesses  peculiar  character- 
istics depending  upon  the  length  of  the  gap  between 
the  ends  of  the  carbons.  When  this  distance  is  too 
small  the  arc  emits  a  peculiar  hissing  noise,  and  is 
called  a  hissing  arc.  It  is  caused  by  a  too  rapid 
volatilization  of  the  carbon,  due  to  the  excessive  cur- 
rent that  would  flow  through  the  lamp  with  a  short 
gap  between  the  carbons.  Spluttering  sounds  pro- 
duced by  the  arc  are  due  to  impurities  in  the  carbon, 
or  loose-grained  carbons.  By  adjusting  the  distance 
between  the  carbons,  a  point  wih1  be  found  where  the 
arc  burns  quietly  and  steady,  and  is  then  termed  a 
normal  or  silent  arc ;  if  this  'distance  be  exceeded  the 
arc  flames.  Impure  carbons,  or  carbons  not  prop- 
erly baked,  will  produce  a  flaming  arc,  which  is  ac- 
companied by  a  loss  of  light  and  rapid  increase  in 
carbon  consumption. 


234  MOTION     PICTURE     PROJECTION 


FILM 

Motion  picture  film  is  a  strip  of  flexible,  supple, 
transparent  celluloid  l^g"  wide.  One  side  of  the  film 
is  given  an  emulsion  coating  much  the  same  as  on 
an  ordinary  photographic  film  pack.  The  margin 
of  the  film  is  perforated,  there  being  64  perforations 
to  the  foot  of  film  or  four  on  either  side  of  each  pic- 
ture (16  pictures  to  one  foot  of  film)  these  perfora- 
tions are  for  the  purpose  of  feeding  the  film  through 
the  camera  or  projector.  The  film  comes  to  the  pro- 
jectionist on  metal  reels,  each  reel  containing  ap- 
proximatly  1,000  feet  of  film,  generally  five  or  six 
reels  making  one  feature  picture.  The  projectionist 
should  always  examine  his  film  before  running  it 
through  the  projector;  this  he  does  by  running  the 
film  from  one  reel  on  to  another,  by  using  a  re- 
winding machine  and  letting  the  film  pass  between 
the  first  finger  and  thumb  of  the  left  hand;  care 
should  be  taken  to  see  that  all  patches  are  se- 
cure, that  the  film  is  free  from  "frame-ups"  and 
that  the  perforations  are  in  such  a  condition 
that  the  film  will  pass  readily  through  the  pro- 
jector without  jumping  off  the  sprockets.  The 
reels  should  then  be  placed  in  a  fireproof  film 
cabinet  in  chronological  order,  care  being  taken  to 
see  that  the  film  is  wound  on  reels  emulsion  side  out 
and  that  the  beginning  of  the  film  subject  comes  off 
first,  in  other  words  that  the  film  does  not  go  through 
the  projector  tail-end  first.  Remember  that  the  film 
passes  through  the  projector  upside  down  and  emul- 
sion side  to  source  of  light.  As  soon  as  the  film  has 
passed  through  the  projector  it  should  be  rewound 


MOTION     PICTURE     PROJECTION  235 

and  placed  back  into  the  safety  cabinet  ready  for 
the  next  show.  The  majority  of  film  exchanges  re- 
quest that  the  film  be  returned  to  them  unrewound 
just  as  it  is  taken  off  the  projector  after  it  has  been 
run,  it  being  the  rule  in  exchanges  that  the  film  be 
examined  starting  at  the  end  and  working  back  to 
the  beginning  of.  the  subject;  this  is  to  eliminate  the 
risk  of  their  sending  the  picture  on  to  the  next 
theatre,  tail-end  first.  Care  should  be  taken  to  see 
that  all  pieces  of  film  are  kept  off  the  floor  of  the 
operating  and  rewinding  room ;  a  special  can  fitted 
with  a  self-closing  door  or  lid  should  be  a  part  of 
the  necessary  equipment  of  the  operating  room. 
Film  should  at  all  times  be  handled  with  great  care, 
as  owing  to  the  ingredients  from  which  it  is  made, 
mtro-cellulose  and  camphor,  it  is  highly  inflammable. 
Never  under  any  circumstances  expose  film  near  a 
naked  light;  do  not  smoke  while  handling  film  or  in 
a  room  where  film  is  stored ;  film  should  not  be  stored 
in  a  warm  dry  atmosphere  unless  it  is  kept  in  a 
humidor.  Do  not  attempt  to  run  a  show  if  using 
inflammable  film  without  having  the  projector  en- 
closed in  an  approved  fireproof  booth;  perhaps  an 
editorial  we  prepared  for  the  Educational  Film 
Magazine  on  this  subject  will  be  appropiate  here. 

In  New  York  State  and,  in  fact,  every  state  of 
the  Union  certain  very  stringent  rules  and  regula- 
tions have  been  drawn  up  and  must  be  complied  with 
before  it  is  possible  to  obtain  a  permit  for  the  pur- 
pose of  showing  motion  pictures.  We  advise  all 
those  in  any  way  interested  in  the  showing  of  motion 
pictures  to  get  a  copy  of  the  law  and  read  it  care- 
fully over. 


236  MOTION    PICTURE     PROJECTION 

The  code  distinctly  states  that  no  motion-picture 
machine  shall  be  used  unless  same  has  been  approved 
by  the  Board  of  Fire  Underwriters.  This  board 
demands  that  all  motion-picture  machine  manufac- 
turers shall  make  the  machines  as  fireproof  as  pos- 
sible; the  machine  must  be  so  constructed  that  only 
a  short  length  of  film  can  be  exposed  while  the 
machine  is  in  operation.  The  machine  must  be  equip- 
ped with  an  automatic  fire  shutter,  so  arranged  that 
the  shutter  will  immediately  drop  in  case  of  trouble 
and  thus  cut  off  the  heat  of  the  arc  lamp  from  the 
film. 

The  law  then  goes  on  to  state  that  even  this  ma- 
chine equipped  as  it  is  with  all  these  fire  prevention 
devices  shall  not  be  used  unless  the  said  machine  is 
installed  in  a  fireproof  booth.  They  are  as  par- 
ticular regarding  the  booth  as  they  are  with  the  ma- 
chine; the  booth  must  be  constructed  of  asbestos, 
concrete,  brick,  or  some  other  approved  fireproof 
material.  Certain  minimum  dimensions  are  given  as 
the  size  of  the  booth  and  it  must  have  a  door  that 
is  automatically  self-closing.  The  projector  and 
observation  ports  in  the  booth  must  be  equipped  with 
metal  or  asbestos  shutters,  so  arranged  that  they 
will  automatically  close  in  case  of  fire  in  the  booth. 
There  must  be  a  flue  or  vent  running  from  the  booth 
to  the  open  air  to  carry  off  the  smoke  in  case  of  fire. 
The  booth  must  also  contain  fire  bucket,  pails  of 
sand,  and  fire  extinguishers. 

Now  that  we  have  a  fireproof  projecting  machine 
installed  in  a  fireproof  booth,  the  authorities  go  one 
better  and  state  that  with  all  these  precautions  there 
is  still  a  great  danger  of  fire  unless  a  duly  qualified 


MOTION     PICTURE     PROJECTION  23T 

licensed  man  is  placed  in  charge  of  the  handling  of 
film  and  the  operating  of  the  projection  machine. 
They  demand  that  theater  managers  shall  take  all 
these  necessary  precautions  against  fire  on  account 
of  the  highly  inflammable  nature  of  the  film.  Both 
the  theater  manager  and  the  professional  operator 
lay  themselves  open  to  severe  penalties  should  they 
not  live  up  to  the  letter  of  the  law.  These  rules  are 
not  laid  down  to  throw  obstacles  in  the  way  of  those 
desirous  of  showing  motion  pictures;  they  were 
drawn  up  after  due  and  careful  consideration  for 
the  public  safety. 

When  we  stop  to  consider  that  a  film  is  run 
to-day  in  a  theatre  where  all  these  very  necessary 
precautions  are  taken,  and  the  following  day  the 
same  film  is  sent  to  some  class-room  or  church,  there 
to  be  run  by  some  amateur  operator  (whose  knowl- 
edge of  projection  is  limited  to  the  threading 
up  of  the  machine  and  the  switching  on  of  the  cur- 
rent) who  is  using  a  projecting  machine  set  up  on 
the  top  of  some  table — minus  the  booth,  minus  the 
various  safety  devices  called  for  by  the  authorities, 
with  probably  hundreds  of  youngsters  crowded 
around  the  machine — we  come  to  the  conclusion  that 
either  too  much  precaution  is  taken  in  the  case  of 
the  theatres  or  not  enough  in  the  church  and  class- 
room. We  come  out  here  and  state  that  it  is  the 
latter.  There  are  hundreds  of  churches,  schools,  and 
educational  bodies  throughout  the  country  which 
are  using  inflammable  film  without  taking  the  neces- 
sary precaution  against  the  ever-present  fire  risk. 

When  inflammable  film  is  used,  it  matters  not  what 
make  of  projector  you  are  using,  you  must  install 


238 


MOTION     PICTURE     PROJECTION 


the  machine  in  a  fireproof  booth  that  has  been  ap- 
proved by  the  proper  authorities,  and  an  experienced 
man  should  be  placed  in  charge.  The  law  is  very 
clear  and  definite  on  this  point. 


MOTION     PICTURE     PROJECTION 


SCREENS 

The  screen  has  in  the  past  been  one  of  the  most 
neglected  features  of  the  average  picture  theatre. 
He  who  states  that  this  or  that  particular  screen  is 
the  best  in  all  cases  is  in  the  same  class  with  the 
country  fair  medicine  vendor  who  calmly  proclaims 
that  his  pill  has  the  virtue  of  curing  all  ills  from 
mange  to  matrimony. 

The  sole  duty  of  a  screen  is  to  reflect  light.  We 
see  the  picture  on  the  screen  not  by  the  light  that 
strikes  the  screen,  but  by  the  light  which  the  screen 
reflects  to  the  eye.  We  would  not  be  able  to  see  a 
picture  projected  onto  a  black  screen,  for  the  simple 
reason  that  there  would  be  no  light  reflected.  Then 
again,  the  screen  that  reflects  the  most  light  need  not 
necessarily  be  the  ideal  screen,  the  manner  in  which 
the  light  is  reflected  must  be  taken  into  consideration. 

There  are  so  many  things  to  consider  when  choos- 
ing a  screen  for  any  particular  installation  that  it  is 
almost  impossible  to  give  general  information  that 
can  be  applied  without  qualification.  The  following 
are  a  few  of  the  points  that  should  be  considered : 

Size  and  shape  of  theatre. 

Is  there  a  balcony? 

Location  of  the  projection  room  in  relation  to  the 
screen. 

Layout  of  seats  as  regards  the  viewing  angle. 

Is  the  screen  to  be  fixed  or  movable,  and  is  there 
to  be  light  behind  it  at  times? 

Distance  from  screen  to  nearest  row  of  seats. 

Kind  and  quantity  of  light  to  be  used  in  projector 
and  its  source. 


240  MOTION     PICTURE     PROJECTION 

Some  further  points  to  be  borne  in  mind  are  these : 
No  screen  reflects  all  of  the  light  that  reaches  it  be- 
cause all  materials  are  more  or  less  absorbent.  No 
screen  can  be  an  efficient  direct  reflector  and  at  the 
same  time  a  satisfactory  diffuser  of  light,  as  these 
two  qualities  are  in  direct  opposition.  In  referring 
to  the  two  classes  of  screens,  it  would  probably  be 
better  to  speak  of  one  as  a  direct  reflector  and  the 
other  as  an  indirect  reflector. 

With  a  given  source  of  light  projected  at  normal, 
i.  e.,  from  directly  in  front  and  viewed  from  the  same 
position,  the  direct  reflecting  screen  will  be  much 


The    Largest    Motion-Picture    Screen    Ever    Constructed.      It 

Measured  165  by  135  Feet.     A  Simplex  Type  "S"  Projector 

Using  170  Amperes,  With  a  Throw  of  350  Feet  Projected  a 

Picture  100  by  75  Feet 


MOTION     PICTURE     PROJECTION 


241 


brighter  than  the  indirect  reflecting  one,  but  when 
viewed  from  angles  the  indirect  reflector  is  the 
brighter,  the  difference  increasing  as  the  angle  in- 
creases. To  the  observers  seated  rather  close  to  the 
screen  of  average  size  the  picture  will  be  more  satis- 
factory if  an  indirect  reflector  is  used,  because  the 


Partially  Finished  Screen 

viewing  angle  varies  considerably  for  different  points 
on  the  screen,  and  consequently  the  picture  would 
not  be  of  uniform  brightness  if  a  direct  reflector 
were  used. 

Generally,  the  direct  reflecting  screens  are  metallic 
surfaced  (there  are  a  few  exceptions),  while  the  in- 
direct reflectors  have  a  non-metallic  (mineral  or  fab- 
ric) surface.  Metallic  surface  screens  generally  show 
very  contrasty  pictures,  the  high  lights  being  very 


242 


MOTION     PICTURE     PROJECTION 


bright  and  glary,  and  the  shadows  very  deep.  There 
is  a  lack  of  graduation  in  the  toning,  however,  so 
that  the  picture  is  deficient  in  fine  detail.  The  in- 
direct reflectors  on  the  other  hand  are  generally  not 
contrasting  because  their  high  lights  are  subdued, 
i.  e.,  not  glary,  and  the  shadows  are  not  so  deep  or 
black  but  the  picture  is  full  of  half  tones,  the  fine- 
ness of  which  depends  largely  upon  the  grain  or 
weave  of  the  material  used  and  its  uniformity. 

The  maximum  in  screen  value  may  be  summed  up 
as  follows : 

Most  light  from  given  current  consumption  or 
high  reflection  and  slight  absorption  of  the  incident 
light.  Uniform  distribution  of  the  reflected  light 
over  a  wide  angle  without  loss  of  brightness.  Detail 
and  half  tones  without  diminishing  contrast  clear, 


Rear  View  of  World's   Largest   Screen   Showing  Tremendous 
Amount  of  Lumber  Used 


MOTION     PICTURE     PROJECTION 


243 


bright  "high  lights"  without  glare,  absolute  opaque- 
ness, great  durability  and  ease  of  transportation  and 
installation,  adaptability  to  different  light  sources, 
such  as  arc  or  incandescent  lamps,  direct  or  alter- 
nating current. 

Since  all  of  these  features  cannot  be  incorporated 
in   anv   one  screen,   it  becomes   necessary   to   decide 


The  Projected  Picture  Could  be  Easily  Seen  Six  Blocks  Away. 
The   Screen   Was    Used   at   the   Methodist   Centenary,   Colum- 
bus, Ohio 

which  one  has  the  best  combination  of  the  above  men- 
tioned points  in  accordance  with  the  requirements  of 
the  auditorium  being  equipped.  While  the  writer 
has  never  made  a  thorough  test  of  the  matter,  he  is 
of  the  opinion  that  it  is  unwise  to  attempt  to  decide 
the  amount  of  current  necessary  for  a  given  installa- 
tion by  considering  only  the  seating  capacity  of  the 
house  and  the  size  of  the  screen.  The  shape  of  the 


244  MOTION     PICTURE     PROJECTION 

auditorium  and  the  arrangement  of  the  seats  in  rela- 
tion to  the  screen  are  matters  of  the  utmost  impor- 
tance when  considering  not  only  the  amount  of  illumi- 
nation necessary  but  also  the  kind  of  screen  upon 
which  the  light  is  to  be  projected,  because  if  the 
room  be  wide  in  proportion  to  the  depth  or  there  is 
a  deep  balcony  with  the  projection  room  at  a  con- 
siderable elevation,  so  that  there  are  some  seats  from 
which  the  viewing  angle  is  greater  than  20  or  25  de- 
grees of  either  the  axis  of  projection  or  of  the  per- 
pendicular face  of  the  screen,  or  both,  it  will  be  neces- 
sary to  install  a  screen  of  the  indirect  reflecting  type 
so  that  the  illumination  will  be  distributed  over  these 
wide  angles,  and  since  distributing  a  given  amount  of 
light  over  a  greater  area  proportionately  reduces  the 
amount  of  light  available  per  degree,  it  will  be  necesi- 
sary,  if  a  given  screen  brightness  is  to  be  maintained, 
to  use  more  current  in  a  house  having  rather  large 
angles  than  would  be  used  if  the  angles  were  not  so 
great.  This  does  not  necessarily  mean  that  as  gen- 
erally used  one  class  of  screen  is  more  costly  in  the 
matter  of  current  than  the  other.  It  all  depends 
upon  whether  or  not  the  screen  is  suited  to  the  house. 
If,  for  instance,  an  indirect  reflecting  screen  is  in- 
stalled in  a  long,  narrow  house,  a  large  proportion 
of  the  light  will  be  reflected  toward  the  side  walls  and 
ceiling  and  wasted.  On  the  other  hand,  if  a  direct 
reflector  screen  be  installed  in  a  house  that  is  rather 
.wide  or  where  the  picture  is  projected  at  an  angle, 
there  will  be  a  pronounced  "fade-out"  or  loss  of  light 
from  all  seats  that  are  not  in  the  direct  reflective 
angle  of  the  screen.  Now,  in  order  to  overcome  the 
fade-out  and  increase  the  light  to  seats  outside  of 


MOTION     PICTURE     PROJECTION  245 

this  direct  reflective  angle,  the  projectionist  usually 
increases  the  incident  illumination  to  a  degree  far 
beyond  the  amount  needed  for  proper  screen  bright- 
ness, a  practice  that  is  not  only  wasteful  as  regards 
electric  current,  but  produces  the  glare  in  the  "high 
lights"  that  is  extremely  unpleasant  to  the  observer 
as  well  as  injurious  to  the  eyes. 

The  screen  should  be  outlined  with  a  dull  black 
border,  and  should  be  placed  so  that  no  light  save  the 
light  from  the  projector  reaches  it.  The  location  of 
the  screen  must  be  governed  by  local  conditions,  but 
it  is  well  to  see  that  it  is  placed  high  enough  so  that 
the  lower  part  of  the  picture  can  be  comfortably  seen 
in  all  parts  of  the  house,  and  yet  not  so  high  that 
those  sitting  down  front  have  to  strain  their  neck 
looking  up  to  the  picture.  Wherever  possible  the 
screen  should  be  placed  so  that  the  center  beam  of 
light  strikes  the  center  of  the  screen  at  right  angles. 
By  doing  this  distortion  and  "keystone  effect"  will 
be  overcome. 


246  MOTION     PICTURE     PROJECTION 


METHOD  AND  APPARATUS  FOR  PROJECT- 
ING MOTION  PICTURES  WITH 
COLOR  EFFECTS 

David  Wark  Griffith  has  received  from  the  Com- 
missioner of  Patents  at  Washington  the  exclusive 
right  to  "make,  use  and  vend  certain  methods  and 
apparatus  for  the  projection  of  motion  and  other 
pictures  with  color  effects." 

The  Griffith  patent,  granting  protection  for  a 
term  of  seventeen  years,  was  secured  by  Albert  L. 
Grey,  Mr.  Griffith's  general  manager,  through  At- 
torney O.  Ellery  Edwards,  and  will  give  the  producer 
ample  protection  against  the  copying  or  appropri- 
ating of  his  lighting  effects  in  color,  first  introduced 
by  Mr.  Griffith  in  connection  with  the  showing  of 
"Broken  Blossoms"  at  the  George  M.  Cohan  Theatre, 
New  York  City. 

The  Griffith  patent  covers  a  wide  range  of  light- 
ing, including  the  process  and  apparatus  by  means  of 
which  either  moving  or  other  pictures  may  be  pro- 
jected onto  an  illuminated  screen  which  has  colored 
lights  blending  with  the  pictures  shown.  These  and 
other  inventions  are  covered  by  the  patent,  the  em- 
bodiment of  which  are  as  follows: 

"The  process  of  producing  colored  pictures  on  an 
opaque  screen,  which  consists  of  throwing  pictures 
by  a  projector  onto  one  surface  of  said  screen  and 
simultaneously  illuminating  the  screen  with  diffused 
colored  lights  thrown  onto  the  same  surface  of  the 
screen  in  a  direction  oblique  to  the  stream  of  light 
from  the  projector. 


MOTION    PICTURE     PROJECTION 


247 


D.  W.  GRIFFITrf. 
•ETMOO  AND  APPARATUS  FOR  PROJECTING  MOVING  AND  OTHER  PICTURES  WITH  C010B  EFFECTS. 

1,334,853.  Patented  Mar,  23, 1920. 

2  SNEETS-tHEIT  I. 


*, 


ft     7 


7    // 


INVENTOR 


CQ< 


\BY 


248 


MOTION     PICTURE     PROJECTION 


"In  an  apparatus  of  the  class  described,  the  fol- 
lowing equipment:  An  opaque  screen,  a  projector,  a 
bank  of  colored  lights  out  of  the  path  of  light  from 
said  projector  and  for  the  purpose  of  throwing 
diffused  colored  light  onto  the  same,  surf  ace  of  said 
screen,  so  that  a  colored  picture  is  shown  when  the 
apparatus  is  in  use." 

Those  who  saw  Mr.  Griffith's  production  of 
"Broken  Blossoms"  during  the  Griffith  repertory 
season  in  New  York,  will  recall  the  illusive  curious 
tinted  lights  that  came  and  went  across  the  surface 
of  the  picture  during  the  unfolding  of  the  story.  The 
scenes  seemed  bathed  in  a  vibrant  mauve,  while  the 
inner  core  of  the  picture  itself  shimmered  with  sal- 
mon pink.  The  symbolic  blue  of  the  Orient  lighted 
the  Chinese  scenes,  and  gave  atmosphere  to  the  por- 
tions of  the  story  wherein  the  Chinaman  figured. 
Words  cannot  do  justice  to  the  photographic  effects, 


MOTION     PICTURE     PROJECTION  249 

many  of  which  were  like  beautiful  moving  canvasses 
colored  by  an  impressionistic  touch. 

Figure  1 — A  perspective  diagrammatic  view  of  the 
preferred  embodiment  of  the  Griffith  invention. 

Figure  2— A  sectional  view  through  the  bank  of 
colored  lights  for  throwing  direct  and  diffused  col- 
ored lights  on  the  screen. 

Figure  3 — A  front  elevation  of  this  bank  of  light. 

DESCRIPTION 

Figure  2 — When  the  trough  (6)  is  bent,  it  forms 
a  suitable  reflector,  and  has  suitable  glow  lamps  (8) 
mounted  therein,  one  in  each  compartment,  and  sup- 
plied with  electricity  from  any  suitable  source  by 
wires  (9). 

Figure  3 — A  long  trough  (6)  has  a  number  of 
partitions  (7)  which  divide  the  space  in  the  trough 
into  several  distinct  compartments,  so  arranged  that 
light  cannot  leak  from  one  to  another.  The  front 
of  the  trough  is  closed  by  a  perforated  plate  (10) 
and  each  perforation  is  closed  by  means  of  a  colored 
diaphragm  or  screen  (11). 

Figure  4 — A  diagram  of  the  wires  and  lights  used 
with  the  Griffith  invention. 

DESCRIPTION 

The  glow  lights  (8)  have  their  wires  (9)  run  to 
the  ordinary  main  wires,  which  are  designated  12 
and  13  for  the  blue  lights,  14  and  15  for  the  red 
lights,  and  16  and  17  for  the  yellow  lights. 

The  blue  lights  are  controlled  by  a  rheostat  or 
dimmer  (18),  the  red  lights  by  a  corresponding  in- 
strument (19)  and  the  yellow  lights  by  another  (20). 
The  wires  (12,  14,  16)  run  to  the  bus  bar  (21) 


250  MOTION     PICTURE     PROJECTION 

and  the  rheostat  (18,  19,  20)  are  connected  to  the 
other  bus  bar  (22).  Wires  23  and  24  connect  these 
bus  bars  through  the  projector  (4)  and  its  regulator 
or  rheostat  (25). 

If  electricity  be  shut  off  the  red  and  yellow  lights, 
and  turned  on  the  blue  lights,  the  entire  screen  will 
appear  blue,  and  the  images  from  the  projector  will 
be  correspondingly  colored.  Also,  by  the  regulators 
or  dimmers  (18  and  25)  the  intensity  of  illumination 
of  the  screen  may  be  varied  so  that  an  infinite  num- 
ber of  color  effects  may  be  produced  with  one  set 
of  colored  lights. 


MOTION     PICTURE     PROJECTION  251 


SIMPLEX-BOYLAN    EVEN    TENSION    REEL 

That  long  neglected  yet  very  important  device, 
the  film  reel  has  at  last  claimed  the  attention  of  the 
machine  manufacturers.  Just  how  many  thousands 
of  dollars  are  wasted  yearly  in  film  damage  due  to 
defective  reels,  will  be  hard  to  say,  but  the  amount 
must  be  enormous.  The  pecular  part  being  that  the 


film  exchanges  are  the  worst  offenders,  sending  out 
features  worth  hundreds  of  dollars  on  reels  that  are 
in  such  a  condition  that  the  film  has  to  materially 
suffer  in  passing  through  the  projector,  or  in  trans- 
portation. The  Simplex  Machine  Co.  were  quick  to 
recognize  the  merits  of  the  reel  designed  by  Grove  S. 
Boylan,  and  after  incorporating  several  improve- 
ments are  now  placing  the  reel  on  the  market  as  the 
Simplex-Boylan  Even  Tension  Reel.  The  reel  is 


252  MOTION     PICTURE     PROJECTION 

light  in  construction  yet  very  strongly  made,  the 
sides  are  made  of  cold  rolled  steel  wire,  which  elimi- 
nates all  rough  sharp  edges,  saving  both  the  film  and 
the  operators  fingers.  The  hub  is  of  die  cast  com- 
position specially  designed  to  prevent  the  slightest 
chance  of  inefficiency. 


Parts  Making  Up  the  Hub  of  Reel 

The  weakest  part  of  every  reel  is  naturally  the 
hub;  often  a  reel  has  to  be  discarded  after  a  few 
weeks  of  service  owing  to  the  keyway  in  the  hub  of 
reel  having  become  badly  worn,  caused  generally  by 
the  strain  it  is  called  on  to  bear  while  the  film  is 
being  rewound.  It  will  be  seen  that  with  the  Sim- 
plex-Boylan  reel  all  parts  liable  to  wear  are  inter- 
changeable making  it  unnecessary  to  discard  the 
whole  reel  should  the  hub  or  any  part  of  it  become 
worn;  then  again  it  will  be  seen  by  referring  to  the 
diagram  that  the  tension  while  rewinding  is  on  the 
key  that  engages  across  the  hub,  rather  than  on  the 
hub  itself,  thus  greatly  increasing  the  life  of  the 
reel. 

The  premier  advantage  is  that  the  projector  take- 
up  can  be  screwed  up  tight  and  thus  put  out  of  com- 
mission, the  Simplex-Boylan  reel  being  so  constructed 
that  it  will  take  care  of  the  film  tension  automatic- 


MOTION     PICTURE     PROJECTION 


253 


ally ;  this  it  does  owing  to  the  friction  caused  by  the 
weight  of  the  reel  and  the  film  which  gives  the  tension. 
The  friction  between  the  reel  and  the  hub,  automatic- 
ally increases  as  the  film  is  wound  on  to  the  hub, 
thus  giving  uniform  tension  from  start  to  finish  of 
picture. 


Simplex-Boylan  Even  Tension  Reel 


254 


MOTION     PICTURE     PROJECTION 


Simplex  Type  "S" 


MOTION     PICTURE     PROJECTION  255 


INSTRUCTIONS  FOR  INSTALLING  THE 
SIMPLEX  PROJECTOR 

Unpacking 

Upon  arrival  of  the  machine  use  utmost  care  in 
unpacking. 

Use  nail  puller  in  opening  case  and  removing  all 
nails  used  in  securing  cleats  supporting  different 
part. 

Never  use  a  hammer  to  knock  out  cleats. 

Cleats  removed ;  parts  can  be  lifted  out  one  by  one. 

Pay  special  attention  when  removing  Mechanism 
from  case. 

Don't  take  hold  of  shutter  shaft  to  lift  it  out. 

Take  hold  of  bottom  with  right  and  top  with  left 
hand  thus  lifting  it  out  of  case. 

Unusual  strain  will  bend  shutter  shaft. 

Simplex  Machines  while  simple  and  strong  in  con- 
struction, are  a  carefully  adjusted  piece  of  mechan- 
ism and  cannot  be  handled  roughly  beyond  a  certain 
limit. 

Setting  Up  Simplex  Projector 

A.  Assemble  pedestal  column  to  base. 
Have  two  feet  of  base  face  screen. 

B.  Fasten  lower  magazine  and  take-up  to  base. 
Use  two  screws  furnished  for  the  purpose. 

C.  Fasten  mechanism  to  pedestal  top  by  means  of 
two  wing  screws. 

D.  Attach  upper  magazine  to  top  of  mechanism. 

E.  Assemble  Lamphouse  to  carriage  just  back  of 
Mechanism. 


256  MOTION     PICTURE     PROJECTION 

Connecting  Up  Asbestos  Leads 
D.  C. 

Attach  three  (3)  ft.  wire  to  Lamphouse  and  lower 
switch  box  terminal. 

Attach  four  (4)  ft.  wire  to  opposite  lower  switch 
box  terminal  and  to  one  side  of  rheostat. 

Attach  six  (6)  ft.  length  to  other  side  of  rheostat 
and  connect  other  end  to  upper  carbon  holder. 

A.  C. 

In  connecting  transformers  or  current  savers,  con- 
nect wires  from  main  line  switch  or  wall  switch  to 
upper  terminals  on  pedestal  switch.  Now  connect 
two  wires  from  lower  terminals  on  above  switch  to 
primary  winding  of  whatever  transforming  device  is 
used,  which  will  be  found  marked  "line."  Then  con- 
nect two  wires  from  terminals  marked  "lamp"  on  the 
transforming  device,  after  which  connect  other  two 
ends  of  these  two  wires  to  the  upper  and  lower  carbon 
holders  inside  of  lamphouse. 

Condenser 

Place  61/2  in-  condenser  toward  arc  and  7%  i*1- 
toward  screen. 

Lens  Assembly 

The  flat  surface  of  the  moving  picture  lens  should 
face  the  arc;  the  bevel  side  the  screen.  This  also 
applies  to  achromatic  lenses. 


MOTION     PICTURE     PROJECTION  257 

Shutter,    Stereo   Lens   Holder   and   Framing 
Device 

Shutter  should  be  placed  on  shutter  shaft  in  front 
of  mechanism  in  accordance  with  instructions  in  fol- 
lowing pages. 

The  framing  handle  should  be  inserted  in  framing 
device  on  lower  part  of  mechanism  facing  lamphouse. 

Take  lens  holder,  insert  lens  between  adapters, 
tighten  with  holder  ring  and  fasten  to  upper  part  of 
mechanism  away  from  operator  with  stereo  rod  in- 
serted in  stereo  arm. 


Attaching  Motor 

For  the  attaching  of  the  Motor  Table  a  slot  will 
be  found  on  the  left  of  the  pedestal  column,  nuts 
and  washers  for  fastening  same  are  furnished. 

Two  sets  of  holes  will  be  found  on  Motor  Table, 
either  set  of  which  may  be  used  according  to  drive. 
When  using  old  style  drive  in  conjunction  with 
pedestal  pulley,  use  inner  set  of  holes.  If  motor  is 
to  be  used  in  connection  with  new  speed  control,  use 
the  outer  set.  Two  5/16  in.  wing  screws  are  fur- 
nished for  fastening  motor  to  table.  After  attaching 
motor  to  table,  fasten  snap  switch  to  slide  over  arm 
for  which  three  holes  are  provided.  The  canvasite 
cord  attached  to  the  snap  switch  should  then  be 
connected  to  the  line  intended  to  furnish  power  for 
the  motor  by  means  of  an  attachment  plug  or  other 
device.  On  AC  when  using  constant  speed  induction 
motor  furnished  with  the  new  friction  speed  con- 
troller, a  10  ampere  fuse  is  recommended,  as  this 


258  MOTION     PICTURE     PROJECTION 

motor  requires  about  three  times  the  normal  running 
current  for  starting  under  full  load. 

On  DC  Motors  a  three  ampere  fuse  is  of  sufficient 
capacity  and  is  recommended  for  the  protection  of 
the  motor. 

Lower  magazine  has  a  reversible  take-up  pulley 
with  two  grooves.  The  large  grooves  should  be  used 
with  the  long  take-up  belt  for  large  reels,  5  in.  hub, 
taking  1,000  ft.  of  film  or  over.  The  small  groove 
should  be  used  with  the  small  take-up  belt  with  reels 
having  small  hub.  If  take-up  does  not  work  properly, 
reverse  pulley,  you  may  have  it  on  wrong. 


MOTION     PICTURE     PROJECTION  259 


Simplex  Mazda  Equipment 


262 


MOTION    PICTURE    PROJECTION 


against  going  back  on  him  it  must  be  designed  right 
in  the  first  place. 

Now,  there  are  two  ways  of  designing  a  Take-up 
Shaft. 

One  way  is  to  design  it  wrong,  to  have  the  belt 
pull  sideways  on  the  shaft,  cramping  it  in  its  bear- 
ings, and  then  to  try  to  overcome  the  difficulty  by 
introducing  ball  bearings. 

The  other  way  is  to  design  it  correct  in  principle, 
like  the  Simplex  Take-up  Shaft  here  illustrated. 

When  you  read  the  explanations  you  will  quickly 
see  that  the  belt-pull  doesn't  come  on  the  shaft  at 
all;  so  there's  no  cramping  or  friction  to  try  to 
reduce  by  "anti-friction"  bearings. 

And,  as  you  know,  the  probability  of  any  piece 
of  mechanism  going  wrong  increases  directly  as  the 


The  Heart  of  the  Simplex 


MOTION     PICTURE     PROJECTION 


263 


number  of  parts  it  contains.  So  being  extremely 
simple  as  well  as  free  from  blunders  in  design,  the 
Simplex  Take-up  Shaft  is  dependable  in  the  highest 

decree. 

The  Intermittent  Movement 

The  Simplex  embodies  the  "star  and  geneva" 
movement,  this  principle  being  as  highly  refined  as 
is  possible  to  do  with  the  best  procurable  material 
and  precision  workmanship. 

No  other  intermittent  movement  has  yet  been 
evolved  which  compares  with  the  geneva  movement 
for  accuracy,  length  of  wear  and  yet  allows  for  per- 
fect adjustment  to  compensate  for  any  amount  of 
wear. 

Movement  lies  in  oil  chamber,  the  lubrication  for 
which  is  conveyed  through  .oil  tubes  easily  accessible. 
•  Shafts  and  sleeve  bearings  are  ground  fit,  insuring 
long  service  and  perfect  fit  and  alignment. 

Adjustment  of  star  and  cam  is  made  by  means  of 
eccentric  bushing  and  by  use  of  fork  wrench  without 
removing  any  portion  of  the  mechanism. 


Diagram  showing  progressively  the  operation  of  the  Geneva 
intermittent  movement 


264  MOTION     PICTURE     PROJECTION 

Complete  intermittent  unit  may  be  removed  en- 
tirely and  replaced  in  two  minutes,  only  tools  re- 
quired for  so  doing  being  screw  driver  and  pliers. 

Casing  is  absolutely  dust-proof,  insuring  against 
abnormal  wear. 

All  mechansm  adjustments  that  are  most  generally 
used  are  located  within  easy  reach  of  the  user's  left 
hand. 

1,  2,  3 — Are  used  for  making  all  stereopticon  ad- 
justments. 

4 — Focuses  the  projector  lens  which  is  contained 
within  the  mechanism,  this  method  of  focusing  doing 
away  with  the  common  practice  of  reaching  in  front 
of  the  mechanism  to  focus  lens  and  the  attending 
danger  while  so  doing  of  knocking  against  revolving 
shutter. 

5 — Indicates  knob  which  locks  door  cover  lower 
loop. 


Accessibility  of  Adjustments  on  Simplex  Projector 


MOTION     PICTURE     PROJECTION  265 

6 — Enables  the  user  to  adjust  shutter  while  ma- 
chine is  in  operation,  this  being  an  exclusive  Simplex 
feature. 

7 — Indicates  frame  lever  so  arranged  to  give  per- 
fectly balanced  leverage  with  the  least  possible 
exertion. 


266  MOTION     PICTURE     PROJECTION 


Simplex  Type  "B' 


MOTION     PICTURE     PROJECTION  267 

VARIABLE  SPEED  CONTROL 

Installation  and  Operation 

When  it  is  desired  to  change  from  hand  driven 
machines  to  motor  driven,  simply  loosen  up  the  set 
screw  (three  turns)  which  holds  the  motor  drive 
pulley  shaft  in  the  lug  on  the  base  of  the  mechanism 
frame.  The  driving  shaft  on  the  speed  control, 
S-575-X  (page  314),  which  has  a  small  gear  on  it,  is 
then  inserted  into  the  hole  in  the  lug  on  the  base  of 
the  mechanism  frame. 

In  attaching  the  device,  it  is  very  important  that 
care  should  be  taken  to  mesh  the  gear  on  the  shaft 
of  the  speed  control  S-575-X  with  the  main  driving 
gear  on  the  mechanism.  The  set  screw  should  then 
be  tightened.  At  the  same  time,  the  idler  pulley  shaft 
on  the  pedestal  fits  into  the  opening  on  the  right  of 
the  speed  control,  and  is  tightened  with  the  knurled 
head  or  wing  screw  from  underneath,  but  the  set 
screw  to  hold  the  driving  shaft  should  be  fastened 
first.  Fasten  the  right  end  of  the  speed  control  at 
whatever  position  it  takes  on  the  idler  pulley  shaft 
on  the  pedestal.  Do  not  force  it  into  position,  as 
it  may  cause  the  gear  on  the  speed  control  and  the 
main  driving  gear,  to  bind,  and  eventually  ruin  them 
by  wearing  unevenly.  The  important  thin£  is  to  see 
that  the  two  gears  mesh  properly  and  the  remainder 
of  the  speed  control  will  take  the  position  which  will 
give  best  results. 

To  install  the  device  on  motor  driven  machines 
you  have  to  remove  the  motor  drive  pulley  on  the 
main  driving  shaft  also  the  idler  pulley  on  the  pedes- 


268 


MOTION     PICTURE     PROJECTION 


tal  shaft.  Place  the  speed  control  on  the  machine 
in  the  same  manner  as  described  above  for  changing 
from  hand  driven  machines  to  motor  driven. 

The  present  D.  C.  Motors  can  be  used  by  making 
a  slight  alteration  in  them,  but  in  the  case  of  alter- 
nating current,  a  new  constant  speed  induction  type 
of  motor  is  provided.  This  abolishes  the  commutator 
type  of  motor  and  means  lower  maintenance  costs  and 
longer  life  of  motors. 

The  arrangement  of  the  belt  for  the  speed  control 
is  shown  in  the  accompanying  illustration  Fig.  C 
better  than  could  be  described  in  a  few  words.  The 
illustration  amplifies  the  description  for  placing  the 
speed  control  on  the  machine. 


Fig.  C 


MOTION     PICTURE     PROJECTION  269 

It  may  be  advisable,  however,  to  give  a  few  details 
in  connection  with  the  operation  of  the  device. 

The  variable  speed  control  is  operated  or  con- 
trolled by  Handle  S-438-M  (page  314).  By  turning 
this  handle  either  to  the  left  or  right,  the  movement 
of  it  either  tightens  or  releases  the  Tension 
Spring  F-119-X  and  moves  the  friction  disc 
S-218-L.  This  .  friction  disc  S-218-L  operates 
between  the  two  other  discs  X-7  and  D-118-X. 
At  any  time,  it  is  only  the  rim  of  the 
friction  disc  S-218-L  that  comes  in  contact 
with  the  other  discs  X-7  and  D-118-X.  When  the 
handle,  is  turned  so  that  the  contact  of  the  friction 
disc  is  near  the  center  of  the  other  discs,  the  speed 
is  low  because  the  contact  is  almost  at  the  center 
of  the  circle  of  the  two  discs  and  revolves  on  a  small 
circumference.  As  the  friction  disc  S-218-L  is  mov- 
ed out  near  the  edge  of  X-7  and  D-118-X  the  cir- 
cumference of  the  circle  increases,  and  the  speed  is 
correspondingly  increased. 

It  is  absolutely  necessary,  if  the  friction  disc 
S-218-L  is  to  drive  the  control  and  the  mechanism, 
that  it  have  a  friction  contact. 

No  oil  of  any  description  can  be  used  on  the  fric- 
tion discs  or  the  other  discs.  And  further,  as  oil 
may  accumulate  on  these  discs  from  time  to  time 
from  the  shaft,  the  discs  must  be  wiped  off  occasion- 
ally. As  soon  as  the  oil  accumulates,  friction  is 
eliminated,  the  speed  reduced  and  the  device  may 
stop  entirely.  A  small  amount  of  vaseline  may  be 
applied  to  the  fibre  disc  occasionally ;  it  should,  how- 
ever, be  wiped  clean  after  applying. 

It  also  must  be  borne  in  mind  that  the  nuts 
N-136-X  holding  the  spring  on  the  shaft  S-470-X 


270 


MOTION     PICTURE     PROJECTION 


must  not  be  tightened  too  much;  just  enough  to 
catch  the  thread  sufficiently  to  hold  the  spring,  as 
a  very  little  pressure  on  the  discs  is  required  to  run 
the  control. 


PLATE   1 


MOTION     PICTURE     PROJECTION  271 

In  changing  the  speed,  the  idler  pulley  moves  with 
the  tension  spring  F-119-X,  and  adjusts  the  belt  so 
that  no  matter  what  speed  is  required,  the  belt  ad- 
justs itself  to  requirements. 

THREADING   SIMPLEX 

To  thread  the  film  through  the  Simplex  head,  open 
up  film  rollers  A  and  D,  Plate  1,  open  gate  by  press- 
ing plunger  B;  now  draw  out  of  upper  magazine 
through  magazine  valve  about  three  feet  of  film,  pass 
film  under  top  feed  sprocket  and  close  film  roller  A, 
thread  through  gate,  making  sure  that  the  film  is 
riding  on  runners;  engage  film  on  teeth  of  intermit- 
tent sprocket,  then  close  gate  by  tripping  catch  C ; 
next  pass  film  over  lower  feed  sprocket  and  close 
film  rollers  D,  thread  through  the  lower  magazine 
valve  and  engage  on  clip  on  lower  reel.  Care  must 
be  taken  to  see  that  a  loop  of  film  is  formed  between 
the  upper  sprocket  and  gate,  and  between  the  inter- 
mittent and  lower  sprocket. 

BEFORE    STARTING  YOUR   SHOW 

See  that— 

Carbons  are  long  enough  to  last  through  the  pic- 
ture. 

Lamphouse  is  free  from  grounds. 

All  electrical  c'onnections  are  tight. 

Arc  is  not  burning  upside  down. 

The  light  spot  is  focused  on  aperture  in  gate. 

Projector  is  oiled,  intermittent  bath  is  full,  grease 
cups  are  filled  and  are  feeding. 

Magazines  are  lined  up  with  mechanism,  so  that  film 
travels  in  a  straight  path  from  top  to  lower 
magazine. 


272  MOTION    PICTURE     PROJECTION 

Take-up  tension  is  all  right,  if  using  Simplex-Boylan 
reels,  see  that  take-up  on  machine  is  out  of 
commission. 

Sprockets  are  free  from  dirt ;  remember  that  dirt  on 
the  intermittant  sprocket  may  cause  jumping 
of  the  picture  on  the  screen. 

Tension  springs  on  gate  of  projector  are  adjusted 
properly. 

There  is  no  deposit  of  emulsion  on  the  tension  springs 
and  shoes. 

Light  or  revolving  shutter  is  synchronised  with  in- 
termittent sprocket. 

Reels  on  which  films  are  wound  are  in  such  a  condi- 
tion that  the  film  runs  off  same  unhampered. 

Lenses  and  condensers  are  clean. 

Picture  is  in  focus,  and  in  frame. 


MOTION     PICTURE     PROJECTION  273 

INSTRUCTIONS     FOR     SETTING    UP     SIM- 
PLEX  MAZDA   EQUIPMENT 

The  Condensers 

Condensers  (J — fig.  1)  will  be  found  wrapped 
with  paper  covering.  Note  that  sizes  of  condensers 
(6%  and  7%)  are  plainly  marked  on  wrappings. 

Unscrew  condenser  rings  (M — fig.  1)  and  drop 
condensers  into  same  carefully. 

Screw  condenser  holder  ring  back  in  to  place  se- 
curely enough  to  hold  condenser.  Great  care  must 
be  taken  against  tightening  this  ring  too  firmly,  as 


by  so  doing  will  bind  condenser  and  prevent  expan- 
sion when  same  becomes  heated,  resulting  in  possible 
breakage. 

When  this  has  been  done  condenser  holders  con- 
taining condensers  are  then  dropped  into  containers 
(N — fig.  1)  with  rounded  or  convex  surfaces  facing 
one  another. 

Note  that  the  6%  condenser  sets  in  container 
nearest  the  lamp  and  the  7%  condenser  sets  in  con- 
tainer nearest  the  film. 


274  MOTION     PICTURE     PROJECTION 

Now  swing  condenser  mount  back  into  position, 
locking  the  same  by  engaging  handle  (I — fig.  1) 
with  lock  (K— fig.  1). 

Placing  Lamphouse  on  Machine. 

Lamphouse  is  now  placed  on  swinging  table,  mak- 
ing sure  that  sliding  base  (P — fig.  1)  sets  accurately 
into  base  groove  (Q — fig.  1),  then  fasten  lamphouse 
to  base  with  wing  screw  (R — fig.  1). 

Setting  Lamp  in  Holder. 

Loosen  knob  (H — fig.  1),  turning  same  out  to  its 
fullest  extent,  then  screw  lamp  (O — fig.  1)  into  its 
socket,  as  far  as  possible. 

Adjust  lamp  so  that  filament  (T — fig.  2)  is  paralr 
lei  with  knob  (F — fig.  2).  This  lining  up  of  filament 


is  imperative  and  absolutely  necessary  in  procuring 
correct  focus,  as  will  be  later  described. 

When  proper  alignment  has  been  made,  tighten 
knob  ( H — fig.  1 )  firmly ;  this  operating  rigidly  se- 
cures lamp  into  required  position  (see  illustration, 
fig.  4). 


MOTION     PICTURE     PROJECTION  275 

Inserting  Lamp  and  Holder  into  Mechanism. 

Lamp  and  holder  are  now  ready  for  inserting  into 
lamphouse. 

Hold  knob  (F — fig.  4)  and  thumb  piece  (S — fig. 
4)  securely  between  thumb  and  forefinger  of  the 
right  hand. 

Insert  lamp  slowly  into  position,  making  sure  that 
collar  (U — fig.  4)  engages  with  rod  (U-l — fig.  6), 
and  also  note  that  contact  strip  (V — fig.  5)  engages 
between  slot  and  contact  holder  (W — fig.  5),  push- 
ing in  as  far  as  it  will  go. 

Inserting  Mirror. 

We  have  now  reached  that  stage  where  the  mirror 
plays  an  important  part  in  our  system. 

Clean  and  polish  mirror  carefully  with  clean  soft 
tissue  paper. 

Now  loosen  thumb  screws  (X — fig.  2)  and  insert 
mirror  (L — fig.  1)  carefully  into  holder  (Y — fig.  2), 
tightening  thumb  screws  (X — fig.  2)  only  sufficiently 
to  hold  mirror  in  place  without  undue  pressure. 

'» 

Focusing  Mirror. 

The  distance  from  the  center  or  back  of  convex 
surface  of  mirror  and  the  filament  (T-2)  of  the  lamp 
should  be  approximately  five  inches,  as  shown  in 
Optical  Diagram  (page  276). 

This  distance  is  obtained  by  operating  knob  (A-l) 
either  to  the  right  or  left  as  occasion  may  require. 

Now  unlock  mirror  holder  by  turning  knob  (D-l) 
to  the  left. 

Now  swing  mirror  to  one  side  as  far  as  possible 
by  means  of  knob  (C-l)  and  lock  same  into  position 


MOTION    PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION 

by  turning  knob  ( D-l )  to  right.    This  throwing 
mirror  to  one  side  is  done  in  order  to  prevent  mir 
image  from  being  confused  with  lamp  filament,  as  ' 
be  described  later. 


PLATE  4 

Focal  Distances. 

Attention  is  now  called  to  the  Optical  Diagr 
(page  276),  which  shows  the  approximate  distan 
to  be  used  as  a  basis  of  operation  between  the  miri 
the  condensers  and  the  cooling  plate  of  the  machi 


278 


MOTION     PICTURE     PROJECTION 


~n 


MOTION     PICTURE     PROJECTION  279 

Should  a  quarter  size  (!%"  diameter)  projector 
lens  be  used  it  is  now  necessary  to  place  ruler  against 
the  surface  of  the  7^2  inc^  (front)  condenser  and 
move  lamphouse  slowly  forward  or  backward  until 
a  distance  of  nine  inches  separates  the  front  con- 
denser surface  from  the  film  position  or  aperture 
plate  on  mechanism. 

Should  the  half  size  (2%"  diameter)  projector 
lens  be  used,  this  distance  should  be  increased  to 
eleven  inches. 

Adjusting  Lamp. 

Turn  knob  (B — fig.  1),  which  is  used  to  carry 
lamp  carriage  forward  and  backward,  until  lamp 
filament  (T — fig.  2)  is  3%  inches  away  from  flat 
surface  of  6^/2  (rear)  condenser. 

Connecting  Up  Apparatus. 
(For  alternating  current) 

We  are  now  ready  to  connect  the  apparatus  with 
regulator,  as  designated  in  diagram  marked  "A.  C. 
Wiring  Diagram"  (page  278). 

Note  that  this  diagram  is  based  on  voltages  rang- 
ing from  95  to  120  inclusive. 

It  will  be  noted  that  the  ammeter  for  registering 
lamp  amperage  will  be  found  packed  separately  in 
carton  which  comes  in  lamphouse  shipping  case. 

This  ammeter  is  to  be  attached  to  bracket  on  rear 
of  lamphouse,  as  designated  in  A.  C.  Wiring  diagram, 
by  means  of  screws  located  in  bracket. 

Warning — In  no  case  should  ammeter  be  placed 
onto  regulator,  as  it  will  not  register  properly  in  this 
location,  owing  to  electrical  disturbances. 


280 


MOTION     PICTURE     PROJECTION 


0 

°<f~  ~~3^ 

h 

0 

0      *^~~~i? 

0 

o 

o 

ON01..0-.II   CJV31 

/_ 

MOTION     PICTURE     PROJECTION  281 

Turn  knob  (B — fig.  1)  which  is  used  to  carry  lamp 
carriage  forward  and  backward  until  lamp  filament 
(T — fig.  2)  is  3%  inches  away  from  flat  surface  of 
61/2  (rear)  condenser. 

Connecting  Up  Apparatus. 
(For  direct  current) 

We  are  now  ready  to  connect  the  apparatus  with 
regulator  as  designated  in  diagram  marked  "Wiring 
for  Single  Lamp  on  Direct  Current"  (page  280).  ' 

Note  that  this  diagram  is  based  on  voltages  rang- 
ing from  95  to  120,  inclusive. 

It  will  be  noted  that  there  are  two  resistance  units. 
One  a  fixed  resistance  or  "cage  type,"  the  other  a 
plate  or  dial  type. 

Attention  is  called  herewith  to  the  ammeter,  which 
is  mounted  upon  the  latter  dial  resistance  plate. 

Turn  regulator  handle  on  dial  to  the  right  until 
it  reaches  the  stop. 

Now  throw  the  machine  switch  in  and  out  quickly, 
or  "flash"  it,  watching  ammeter  carefully  in  order 
to  determine  whether  it  is  registering  forward  or 
backward. 

If  ammeter  registers  backward,  disconnect  the  two 
leads  on  the  dial  resistance  and  reverse  them.  This 
should  have  the  effect  of  changing  the  polarity. 

After  again  making  the  connections  secure,  repeat 
the  "flash"  on  the  machine  switch  in  order  to  be  as- 
sured of  the  correct  polarity. 

If  polarity  is  correct,  leave  machine  switch  in. 
This  will  result  in  ammeter  registering  a  reading  of 
something  over  35  amperes.  This  should  cause  no 


282 


MOTION     PICTURE     PROJECTION 


3    r 


\ 

a 

f 

1 

3  ' 

r 

0 

L-- 

b 

/ 

~~  P1X 

i 

1 

* 

0     J 

1 

J,  fe 

2 

*     0 

0 

I! 


MOTION     PICTURE     PROJECTION 


283 


concern,  as  the  amperage  will  drop  to  approximately 
25  amperes  within  a  moment  or  two. 

Note : — The  ammeter  must  be  closely  watched  dur- 
ing the  burning  period  of  the  lamp  and  must  in  no 
case  exceed  the  lamp  rating,  which  is  indicated  on 
metal  base  of  lamp. 


PLATE  5 

Now  lift  up  fire  shutter  on  mechanism  and  fasten 
same  by  inserting  tooth-pick  or  match  behind  same 
in  such  a  manner  that  fire  shutter  will  remain  open. 

Now  lift  dowser  on  lamphouse  hood ;  this  will  allow 
the  light  to  be  centered  on  fire  shutter  on  mechanism 
as  indicated  in  fig.  7. 


284 


MOTION     PICTURE     PROJECTION 


I 

r 

n 

m 

95-120  VOLTS  ^SAMR  f 
0  erect 

i 

b 

\\ 
\\ 

f  2 

*r 

i! 


MOTION     PICTURE     PROJECTION  285 

Focusing  Lamp. 

It  is  necessary  that  this  circle  of  light  shall  cut  all 
corners  of  cooling  plate,  as  shown  in  fig.  7. 

Should  the  light  circle  be  either  too  high  or  too 
low,  adjustment  for  bringing  it  into  true  position  is 
made  by  operating  knob  (E — fig.  1)  and  watching 
results  on  cooling  plate. 

Should  circle  of  light  be  to  one  side,  loosen  thumb 
screw  (G — fig.  1),  then  turn  knob  (F — fig.  1)  for- 
ward or  backward,  as  may  be  necessary,  until  circle 
of  light  is  in  true  position  on  cooling  plate. 

Should  it  be  necessary  in  this  operation  to  adjust 
lamp  to  left,  it  is  necessary  to  push  firmly  against 
knob  (F.I)  in  order  to  produce  proper  movement  of 
lamp. 

Locking  Lamp. 

When  this  adjustment  has  been  satisfactorily 
made,  tighten  thumb  screw  (G — fig.  1)  securely. 
This  operation  locks  knob  (F — fig.  1),  preventing 
lamp  from  loosely  swinging  should  the  lamp  holder 
be  taken  out. 

Focusing  Lamp  Filament  on  Card  or  Shutter. 

Now  it  is  necessary  that  the  lamp  filament  be 
focused. 

We  now  remove  the  projector  lens  from  mechanism 
and  move  revolving  shutter  out  on  shutter  shaft 
until  a  distance  of  10%  inches  separates  the  cut-off 
blade  on  shutter  from  the  aperture  plate  or  film  posi- 
tion on  mechanism. 

Should  it  not  be  convenient  to  use  revolving  shut- 
ter for  this  purpose,  a  card  may  be  placed  in  the 


286 


MOTION     PICTURE     PROJECTION 


same  position,  making  sure,  however,  that  the  dis- 
tance of  10%  inches  is  maintained. 

We  now  have  an  image  of  the  lamp  filament  out- 
lined on  the  shutter  blade  or  card,  as  indicated  in 
fig.  8.  If  image  is  not  in  exact  focus,  check  up  care- 
fully all  measurements.  If  measurements  are  all  cor- 
rect, it  is  now  necessary  to  sharpen  up  or  focus  fila- 
ment by  turning  knob  (B — fig.  1)  either  to  right  or 
left  until  the  filament  is  clearly  outlined  upon  card 
or  shutter  blade. 

Results  on  Focusing  Card  or  Shutter. 
Now  unlock  mirror  by  turning  knob  (D-l.)  to  left 
and  swing  mirror  over  by  means  of  knob  (C-l.). 


MOTION     PICTURE     PROJECTION  287 

We  now  see  besides  the  lamp  filament  on  the  card 
or  shutter  another  image;  this  is  much  fainter  in 
definition  than  the  lamp  filament.  This  faint  image 
is  called  the  mirror  image. 

It  is  now  necessary  to  sharpen  this  up  as  much  as 
possible;  this  is  done  by  adjusting  mirror  (L.I), 
turning  knob  (A-l)  forward  or  back  until  clear 
definition  is  obtained. 

It  is  now  necessary  to  center  mirror  image  in  same 
position  as  the  filament  image. 

By  swinging  knob  (C-l)  to  right  will  register  mir- 
ror to  left,  and  vice-versa. 

Should  mirror  filament  register  too  high  or  too 
low,  immediate  true  position  may  be  obtained  by 
turning  knob  (C-l)  to  right  or  left. 

Merging  Both  Filaments. 

Now  that  both  filaments  show  up  sharp  and  are 
both  in  relative  position,  swing  mirror  oyer  by  means 
of  knob  (C-l)  ;  this  will  move  mirror  image  over  on 
card  or  shutter,  the  purpose  being  to  register  the 
mirror  image  filament  in  between  the  open  spaces  of 
the  lamp  filament,  as  shown  in  fig.  9. 

Locking  Mirror. 

Now  make  sure  that  the  results  on  card  or  shutter 
are  all  that  should  be  desired,  and  lock  mirror  into 
position  by  turning  knob  (D — fig.  1)  to  right. 

Increased  Amperage. 

(Direct  current) 

After  the  lamp  and  resistance  have  become  suf- 
ficiently warmed  up,  turn  the  dial  handle  slowly  to 
the  left,  carefully  watching  the  ammeter  until  the 
indicator  of  same  registers  30  amperes. 


288  MOTION     PICTURE     PROJECTION 

Increasing  Amperage. 
(Alternating  current) 

Now  bring  lamp  up  to  full  capacity  of  30  amperes 
by  turning  regulator  handle  to  right,  while  carefully 
watching  ammeter  until  same  registers  at  30  amperes. 

Warning — Do  not  under  any  circumstances  ex- 
ceed 30  amperes,  as  by  so  doing  will  result  in  the 
overloading  and  subsequent  damage  to  lamps. 

Clear  Field  of  Light. 

We  now  have  the  lamp  at  full  amperage. 
Replace  projector  lens  into  mechanism. 
Focus  same  up  sharply. 

Screen  should  now  show  a  clean,  evenly  distributed 
field  of  light. 


PLATE  7 


MOTION     PICTURE     PROJECTION  289 

Should  any  discoloration  or  shadows  be  apparent 
on  screen,  slide  lamphouse  carefully  and  slowly  back- 
ward or  forward  until  discoloration  disappears. 

When  screen  is  all  cleared  up  through  the  fore- 
going operation,  fasten  lamphouse  by  tightening  up 
wing  screw  (R — fig.  1). 

Now  take  away  focusing  card  and  readjust  shut- 
ter (if  necessary),  and  the  equipment  is  ready  for 
operation. 

Adjusting  Extra  Lamp. 

In  order  to  be  prepared  for  any  emergency,  it  is 
wise  to  have  an  extra  lamp  and  holder  all  ready  for 

instant  use. 


PLATE  8 


Follow  instructions  for  setting  lamp  into  holder, 
as  described  in  Section  3,  and  set  to  one  side,  where 
it  will  be  quickly  available. 


290  MOTION     PICTURE     PROJECTION 

Should  same  be  required  while  ^machine  is  in  opera- 
tion, pull  machine  switch,  throw  back  regulator  han- 
dle to  "low"  and  withdraw  burned  out  or  defective 
lamp  and  insert  new  lamp  and  holder  as  described  in 
Section  4. 

CAUTION— MAKE  SURE  THAT  MACHINE 
SWITCH  IS  OFF  BEFORE  WITHDRAWING 
OLD  LAMP. 

Now  throw  in  machine  switch  and  bring  regulator 
up  to  30  amperes. 

Now  center  spot  light  on  cooling  plate,  as  before 
described,  and  get  as  clear  a  field  as  possible  until 
an  opportunity  of  procuring  permanent  readjust- 
ment is  available. 


PLATE  9 


MOTION     PICTURE     PROJECTION  291 


"A   Pocket   Reference  Book 

FOR 

Managers  and  Projectionists' 

By  JAMES  R.  CAMERON 


Price  One  Dollar 
THEATRE  SUPPLY  COMPANY 

124  WEST  45TH  STREET  NEW  YORK  CITY 


292  MOTION     PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  293 


SIMPLEX  PARTS 
(HEAD) 

Name 

S-189-W— Magazine   Bracket   Screw. 

P-207-D— Top  Plate. 

S-194-C — Sprocket  Roller  Arm  Screw. 

A-136-C — Upper  Pad  Roller  Arm. 

W-160-C— Upper  Pad  Roller  Arm  Washer. 

S-248-C— Roller  Holder  Screw. 

S-165-C— Pad  Roller  Arm  Washer  Screw 

P-102-C— Pad  Roller. 

S-248-C — Upper  Magazine  Roller   Holder  Screw. 

C-4— Film  Trap   Trip  Lever 
S-442-G— Intermediate  Shaft  Collar  Set   Screw. 
S-567-C— Pad  Roller  Arm  Stud. 
N-115-C— Sprocket  Roller  Arm  Nut. 
A-137-C— Lower  Pad  Roller  Arm. 
P-102-C— Pad  Roller. 
S-217-C— Pad  Roller  Screw. 
S-161-A — Projecting  Lens  Holder  Screw. 
S-130-E— Film  Guide  Holder  Screws.    - 
S-326-E— Film  Guide  Retain  Spring. 
S-309-E— Film  Trap   Shoe. 

S-192-D — Upper  and  Lower  Left  Door  Hinge  Screw. 
S-137-C— Film  Trap  Door  Trip  Lever  Screw. 
S-329-C— Trip  Lever  Spring. 
S-130-E— Film  Guide  Holder  Screw. 
S-328-E— Film  Trap  Door  Pad  Spring. 
P-100-E— Film  Trap  Door  Pad. 

E-4 — Film  Trap  Door  Complete. 
G-105-B— Fly  Wheel  Shaft  Gear. 
P-279-B— Star  Wheel  Cam  Pin. 
S-551-B— Star  Wheel  and  Shaft. 

B-16— Star  Wheel  Cam  Complete. 
S-162-E— Film  Guide  Retain   Spring  Screw. 

E-3— Intermittent  Film  Guide. 
P-214-E— Film  Projector. 


294 


MOTION     PICTURE     PROJECTION 


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S  1  do  d  6      6  a)  5i 


MOTION     PICTURE     PROJECTION  295 


SIMPLEX  PARTS 
(HEAD) 

Name 

G-147-G— Spiral  Gear. 

G-116-G— Spiral  Gear  with  Broached  Hole. 
G-115-G— Shutter  Drive  Bevel  Gear. 
D-13— Shutter    Spider    Complete. 

Extralite  Shutter. 
W-131-B— Intermittent  Sprocket. 

B-4 — Eccentric  Bushing  and   Sleeve. 

B-8 — Intermittent  Case  Cover. 

B-l— Intermittent  Case. 
G-112-G— Main  Driving  Gear. 
G-148-B— Fly  Wheel  Gear. 
W-152-B— Fly  Wheel. 
C-126-A— Main  Driving  Gear  Clutch. 
P-196-A— Picture   Framing   Handle   Pivot. 
S-118-A — Motor  Drive  Pinion  Set  Screw. 
G-135-G— Intermediate  Bevel  Gear. 
S-141-D— Stereo  Focusing  Knob  Set  Screw. 
G-139-G— Upper  Sprocket  Shaft  Gear. 
G-138-G— Bevel  Gear  No.  3. 
S-133-C— Film  Trap  Screw. 

L-lll-C — Governor  Lift  Lever  Connecting  Link. 
S-101-C— Auto  Fire  Shutter  Hinge  Screw. 
L-110-C— Governor  Lift  Lever   Link. 
S-101-C— Auto   Fire   Shutter   Hinge  Screw. 

D-2— Governor  Lift  Lever   Roller   Complete. 
S-150-D — Governor  Lift  Lever  Pivot  Screw. 
P-107-G— Vertical  Shaft  Gear  Taper  Pin. 
G-120-G— Vertical  Shaft  Gear. 
P-107-G— Vertical  Shaft  Gear  Taper  Pin. 
G-102-G— Bevel  Gear  No.  2. 

A-7 — Framing  Cam   and   Arm. 
G-lll-G— Lower  Sprocket  Gear. 
S-444-G— Intermediate  Shaft. 
S-122-G — Intermediate   Bevel  Gear  Fastening  Screw. 


296 


MOTION     PICTURE     PROJECTION 


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MOTION     PICTURE     PROJECTION  297 

SIMPLEX  PARTS 
(HEAD) 

Name 

S-436-A— Focusing  Knob  Set  Screw. 

R-178-A — Focusing  Knob  Rod. 

K-119-A — Focusing  Pinion  Rod  Knob. 

S-125-A— Eccentric  Bushing  Screw. 

W-145-D— Upper  Feed  Sprocket. 

S-134-E— Film  Trap  Door  Stud  Screw. 

S-106-E— Right   Back  Cover  Latch   Plate  Screws. 

L-116-B— Intermittent  Case  Cover  Lock. 

S-157-B— Intermittent  Case  Cover  Lock  Screw. 

A-117-A — Picture  Framing  Arm. 

L-114-G — Picture  Framing  Connecting  Link. 

K-120- A— Shutter  Adjusting  Screw  Knob. 

S-125- A— Shutter  Adjusting  Screw  Knob  Set  Screw. 

C-ll — Framing  Handle  Complete. 
S-252-A— Shutter  Adjusting  Screw. 
L-107-G — Picture  Framing  Lever. 
A-118-G— Picture  Framing  Handle  Arm. 
N-119-G—Picture  Framing  Lever  Pivot  Screw  Nut. 
W-146-D— Lower  Feed  Sprocket. 
S-429-G— Lower  Sprocket  Shaft. 
S-125-D — Eccentric  Bushing  Screw. 
S-189-W— Magazine  Bracket  Screw. 
S-573-D — Upper  &  Lower  Stripper  Studs. 
S-572-D— Upper  &  Lower  Stripper. 
S-445-G— Upper  Sprocket  Shaft. 
S-165-A— Pad  Roller  Arm  Washer  Screw. 

A-4 — Projecting  Lens  Holder  &  Slide. 
S-574-G— Shutter  Shaft. 
S-192-D— Shutter  Spider  Screws. 
B-122-G— Shutter  Gear '  Bracket. 
S-570-C— Upper  Pad  Roller  Arm  Spring. 
S-342-C— Projecting  Lens  Holder  Slide  Rod  Spring. 
C-192-G— Intermediate  Shaft  Retaining  Collar. 
S-223-G— Framing  Slide  Lever  Stud  Set  Screw. 
S-323-A— Shutter  Adjusting  Slide. 
S-253-A— Shutter  Adjusting  Slide  Set  Screw. 
S-569-C— Lower  Pad  Roller  Arm  Spring. 
S-572-D— Upper  and  Lower  Stripper. 

D-l— Driving  Handle  Compete. 
S-573-D— Upper  &  Lower  Stripper  Stud. 


298 


MOTION     PICTURE     PROJECTION 


W-I26-D 

R-5 

OIL 

S-5I2-B 

C-IOO-A 

S-34K3 

N-II9-G 

S-II5  A 

B-I98-A 


PLATE  4 


MOTION     PICTURE     PROJECTION  299 

SIMPLEX  PARTS 
(HEAD) 

Name 

S-264-D— Stereo  Lens   Adjusting  Screw. 
S-155-R— Stereo  Universal  Clamp  Wing  Screw. 
S-106-D— Stereo  Slide  Stop  Screw. 
A-122-D— Stereo  Arm. 

S-155-R— Stereo  Universal  Clamp  Wing  Screw. 
R-127-R— Stereo  Lens  Adjusting  Rod. 

R-6 — Stereo   Lens    Holder   Universal  Clamp. 
S-432-E— Film  Trap   Shoe   Screw. 
W-126-D— Governor  Weight. 

R-5 — Stereo  Lens  Holder. 
S-512-B— Fly  Wheel  Set  Screw. 
C-100-A — Framing  Cam. 

S-341-G — Picture  Framing  Handle  Friction  Spring. 
N-119-G— Picture  Framing  Lever  Pivot  Screw  Nut. 
S-115-A — Centre  Frame  Screw. 
B-198-A — Mechanism  Base. 
K-102-A — Focusing  Pinion  Knob. 
S-324-D— Stereo  Slide. 
S-l 92-D—  Film  Shutter  Screw. 
S-337-E— Lateral  Guide  Roller  Spring. 
S-292-E— Lateral  Guide  Roller  Shaft. 
R-130-E— Lateral  Guide  Roller. 
S-161-E— Auto.  Fire  Shutter  Stop  Screw. 

E-l— Film  Trap  Complete. 
S-l 02-E— Auto.  Fire  Shutter  Link-  Retain  Screw. 

E-7— Auto.  Fire  Shutter  Lift  Lever. 
L-109-E— Auto.  Fire  Shutter  Lift  Link. 
S-100-E— Auto.  Fire  Shutter  Lever  Screw. 

E-5— Film  Heat  Shield  Complete. 
S-138-E— Film  Trap  Heat  Shield  Retain  Screw. 
S-316-E— Auto.  Fire  Shutter. 
P-263-E— Right  Back  Over  Latch  Plate. 
W-131-B— Intermittent  Sprocket. 
P-153-B— Intermittent  Sprocket  Taper  Pin. 
S-125-B— Eccentric  Bushing  Screw. 
S-124-D— Driving  Arm  Retain  Screw. 
P-209-D— Driving  Arm  Retaining  Plug. 
S-287-A— Handle  Shaft. 
R-133-A — Framing  Cam  Adjusting  Ring. 
C-189-A— Handle  Shaft  Driving  Collar. 
F-100-A— Centre  Frame. 


302 


MOTION     PICTURE     PROJECTION 


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MOTION     PICTURE     PROJECTION  303 


SIMPLEX  PARTS 
(HEAD) 

Name 

D-ll — Left  Door  and  Knob  Complete. 
P-144-D— Left  Door  Lock  Pin. 
S-178-D— Left  Door  Knob  Screw. 
C-151-D— Left  Back  Cover. 

D-19— Lower  Left  Door  Hinge. 
D-12— Lojver  Left  Door  Complete. 

D-8— Right  Back  Cover  Latch  Knob  Complete. 
S-361-D— Intermittent  Sprocket   Stripper. 
S-185-D— Lock  Stop  Screw. 

D-9— Right  Back  Cover  Complete. 

D-7— Right  Back  Cover  Hinge  Complete. 
E-101-D — Medium  Size  Escutcheon. 
B-198-A— Mechanism   Base. 
p_207-D— Top    Plate. 

C-8— Upper  Magazine  Roller  Holder  Complete. 
S-181-D— Left  Door  Stop  Link  Screw. 
L-113-D— Left  Door  Stop  Link. 
C-152-D— Left  Front  Cover. 
C-118-D— Bevel  Glass  Clamp. 
S-l  92-D— Right  and  Left  Door  Hinge  Screw. 

D-18 — Upper  Left  Door  Hinge. 
G-124-D— Right  Door  Glass. 
D-17— Right  Door  Hinge. 
C-159-C— Right  Front  Cover. 

D-5 — Right  Door   and  Knob  Complete. 
C-118-D— Bevel  Glass  Clamp. 

D-6— Right  Door  Lock  Spring  and  Button. 
S-l 65-C— Cover  Screw. 
C-157-C— Right  Cover. 
R-161-C — Large  Magazine  Roller. 
R-160-u— Small  Magazine  Roller. 
S-485-C— Magazine  Roller  Screw. 


304  MOTION    PICTURE     PROJECTION 


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MOTION     PICTURE     PROJECTION  305 


SIMPLEX  PARTS 
(LAMPHOUSE) 

Name 

S-415-Q — Condenser  Holder  Frame  Support. 

F-105-Q— Condenser  Holder  Frame. 

P-233-Q— Hood  Plate. 

H-131-O — Lamphouse  Hood. 

S-525-Q — Condenser  Holder  Frame  Locking  Pivot  Screw. 

R-14 — Condenser  Holder  Sets. 
H-144-Q— Condenser  Holder  Frame   Handle. 
F-lll-Q — Rear   Condenser   Holder   Frame. 
S-125-B— Set  Screw. 

P-225-Q— Condenser  Holder  Frame  Hinge  Pin. 
P-110-F— Cotter  Pin. 

S-408-Q— Slide  Carrier  Retaining  Screw. 
S-145-G— Hood  Plate  Fastening  Screw. 
S-149-Q— Hood  Fastening  Screw. 
O106-R— Slide  Carrier. 

O-10 — Lamphouse  Hood  Dowser  and  Handle. 


306 


MOTION     PICTURE     PROJECTION 


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a.  a  o. 


MOTION     PICTURE     PROJECTION  307 


SIMPLEX  PARTS 
(TAKE-UP) 

Name 

S-438-M— Set  Screw. 
L-119-M— Reel  Lock. 
P-147-W— Reel  Lock  Pin. 
P-160-M— Reel  Shaft  Collar  Pin. 
C-206-W— Magazine  Collar. 
B-195-W— Take-Up  Shaft  Bearing  Bushing. 
A-135-W— Lower   Magazine   Arm,   16". 
P-288-W— High  Speed  Take-Up  Pulley. 
P-287-W— Low  Speed  Take-Up  Pulley  (Not  shown  on  cut.) 
D-122-W— Take-Up  Floating  Friction  Disc. 
P-178-R— Take-Up  Pulley  Pin. 
C-226-U— Friction   Adjusting   Spring  Collar. 
S-331-W— Friction  Adjusting  Spring. 
N-149-U— Friction  Adjusting  Spring  Nut. 
S-560-W— Take-Up  Shaft. 

W-163-W— Take-Up  Friction  Leather  Washer. 
D-121-W— Take-Up   Shaft  Friction  Disc. 
S-422-G — Set  Screw  for  Friction  Disc  (Not  shown  on  cut). 


308 


MOTION     PICTURE     PROJECTION 


C-I83-U 


B-I47-U 
P-235-U 
S-427-U 


C-226-U 
N-I49-U 
S-33I-W 


C-I8I-U 
A-I34-U 
G-I3I-U 


P-I47-M 
PH60-M 


PLATE  9 


MOTION     PICTURE     PROJECTION  309 


SIMPLEX  PARTS 
(MAGAZINE) 

Name 

C-183-U — Upper  Magazine  Cover. 

B-147-U— Magazine  Hinge  Bracket. 

P-235-U— Magazine  Hinge  Pin. 

S-427-U— Magazine  Wire  Glass  Retaining  Plate  Screw. 

C-226-U — Friction  Adjusting  Spring  Collar. 

N-149-U— Friction  Adjusting  Spring  Nut. 

S-331-W— Friction  Adjusting  Spring. 

C-181-U— Upper  Magazine  Case  16". 

A-134-U — Upper  Magazine  Arm  16". 

G-131-U — Upper  Magazine  Door  Wire  Glass. 

C-206-W— Upper   Magazine  Collar. 

U-3— Upper  Take-Up  Shaft. 
L-119-M— Reel  Lock. 
S_438-ivi — Magazine  Collar  Set  Screw. 
P-147-M— Reel  Lock  Pin. 
P-160-M— Reel  Shaft  Collar  Pin. 


310 


MOTION     PICTURE     PROJECTION 


B  8  9 S ? 

d»flCo4>&o±v» 


MOTION     PICTURE     PROJECTION  311 


SIMPLEX  PARTS 
(MAGAZINE) 

Name 

P-235-U— Magazine  Hinge  Pin. 

P-236-U— Magazine  Wire  Glass  Retaining  Plate. 

G-131-U — Lower  Magazine  Door  Wire  Glass. 

S-427-U — Magazine  Wire  Glass  Retaining  Plate  Screw. 

N-135-U— Magazine  Wire  Glass  Retainer  Plate  Nut. 

K-106-D — Lower  Magazine  Door  Knob. 

C-184-W — Lower  Magazine  Cover  16". 

H-143-U — Magazine  Hinge. 

S-138-E— Magazine  Latch  Spring  Retain  Screw. 

P-237-U— Magazine  Latch  Spring  Protector. 

U-l — Magazine  Latch. 

R-4— Take-Up  Belt  for  Reels  with  Small  Hubs. 
H-132-R— Belt  Hook. 

W-l — Lower  Magazine  Roller ,  Holder. 
S-189-W — Magazine  Arm  Screw. 
C-182-W— Lower  Magazine  16". 
A-135-W — Lower  Magazine  Arm  16". 
N-132-U— Magazine  Latch  Spring  Retaining  Nut. 
P-234-U— Magazine  Latch  Spring  Distance  Piece. 

R-10— Take-Up  Friction  Belt  for  Reels  with  Large  Hubs. 
S-187-W — Lower  Magazine  Hinge  Screw. 


312  MOTION     PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  313 


SIMPLEX  PARTS 
(MOTOR) 

Name 

C-162-S— Outlet  Box  Cover  with  Switch  Bridge. 

S-389-S— Snap  Switch. 

B-136-S— y2"  T.  &  B.  Bushing. 

B-123-S — Snap  Switch  Bracket. 

S-108-S— Binding  Post  Cover  Fastening  Screw. 

C-210-S— Canvasite  Cord. 

S-238-G— Switch  Box  Bracket  Fastening  Screw. 

H-127-S— Snap  Switch  Holder. 

S-148-G— Motor  Pulley  Screw. 

N-117-S— Motor  Table  Attachment  Bolt  Nut. 

W-116-S— Motor  Table  Attachment  Bolt  Washer. 

B-110-S— Motor  Table  Attachment  Bolt. 

T-118-L— Motor  Table. 

P-294-X— Motor  Pulley. 

C-209-S— Armored  Cable. 

C-140-S—  %"  Squeeze  Connectors. 

S-170-R— Motor  Fastening  Screw. 


314 


MOTION     PICTURE     PROJECTION 


C-2II-X 
S-437-G 

S-438-M 

K-H7-X 

R-I66-X 


PLATE  12 


MOTION     PICTURE     PROJECTION'  315 


SIMPLEX  PARTS 
(SPEED  REGULATOR) 

Name 

S-178-X— Friction  Disc  Carrier  Stop  Screw. 

G-141-X— Speed  Adjusting  Gear. 

S-487-G— Collar  Set  Screw. 

W-103-D— Starting  Rod  Friction  Spring  Retaining  Washer. 

S-524-X— Starting  Rod  Friction  Spring. 

C-204-X— Starting  Mechanism  Friction  Disc  Carrier. 

R-168-X— Square  Rod  for  Horizontal  Handle. 

N-186-X— Friction  Spring  Nut. 

S-470-X— Friction  Spring. 

S-463-X— Internal  Friction  Disc  Driving  Flange  Set  Screw. 

S-218-L— Set  Screw. 

F-119-X— Speed  Control  Main  Frame. 

G-141-X— Speed  Adjusting  Gear. 

S-437-G — Gear  Set  Screw. 

S-218-I^-Carrier  Set  Screw. 

C-211-X— Starting  Knob  Rod  Collar. 

S-437-G— Gear  Set  Screw. 

S-438-M— Starting  Knob  Set  Screw. 

K-117-X— Speed  Control  Knob. 

R-166-X— Starting  Knob  Rod. 

X-7 — External  Friction  Disc  Complete. 
D-118-X— Internal  Friction  Disc. 

X-ll— Speed  Control  Main  Pulley  and  Oil  Cup. 
S-575-X— Speed  Control  Motor  Pinion  Stud. 

X-5 — Tension  Pulley  Carrier  Complete. 
S-438-M— Speed  Control   Knob  Set  Screw. 

X-8— Idler  Pulley  Carrier  Complete. 


316 


MOTION     PICTURE     PROJECTION 


B-207-: 


D-II4-X 


PLATE  13 


MOTION     PICTURE     PROJECTION  317 


SIMPLEX  PARTS 
(SPEED  REGULATOR) 

Name 

B-207-X— Speed  Control  Belt. 

S-469-X— Tension   Pulley  Carrier  Roller  Screw. 

R-153-X— Tension  Pulley  Carrier  Roller. 

S-472-X— Square  Rod  Friction   Spring. 

S-173-X— Friction  Spring  Screw. 

S-467-X — Main  Frame  Clamp  Screw. 

S-145-G— Pulley  Carrier  Screw. 

D-114-X— Starting  Mechanism  Friction  Disc. 

X-ll— Speed  Control  Main  Pulley  and  Oil  Cup. 

X-8 — Speed  Control  Friction  Disc. 
S-218-L— Set  Screw. 
S-471-X— Belt  Tension  Spring. 
K-117-X— Speed  Control  Knob. 
R-165-X— Speed  Adjusting  Knob  Rod. 
W-107-G— Pulley  Washer. 
P-293-X— Deflecting  Pulley. 


31- 


MOTION     PICTURE     PROJECTION' 


MOTION'     PICTURE     PROJECTION 


SIMPLEX  PARTS 
(PEDESTAL) 

ffi 


S-270-L— Switch  Box  Screw. 

C-105-L— Lampboose  Carriage. 

S-103-F— Lamphouse  Carriage  Handle  Fastening  Screw. 

S-3ST-L—  Knife  Switch  60  Amperes. 

5-52  -L— Auxiliary  Arm  Pivot  Screw. 

H-148-L— Lamphouse  Carriage  Handle. 

W-iia-L— Lamphouse  Carriage  Washer. 

S-37-5-L— Lampbouse  Carriage  Pivot  Stud. 

L-3— Switch,  Box  and  COTCT  Complete  for  60  Amperes. 

L-o — Switch,  Box  and  Cover  Complete  for  100  Amperes. 
A-120-L— Slide  Over  Arm. 
Q-100-L— Quadrant. 

S-172-L— Lamphouse  Carriage  Retain  Screw. 
P-197-L— Slide  Over  Arm  Pivot 
A-116-L— Pedestal  Arm. 
P-256-L—  Pedestal  Arm  Pivot. 
S-218-L— Pedestal  Arm  Pivot  Set  Screw. 
S-520-L— Auxiliary  Arm  Pivot  Screw. 
A-107-L—  Auxiliary  Arm. 
S-229-L— Quadrant  Lock  Retaining  Screw. 
C-137-L— Pedestal  Column. 
L-117-L— Quadrant  Lock. 
S-230-L— Quadrant  Stand  Screw. 

L-2— Quadrant  Lock  Clamp  Handle  and  Set  Screw. 

L-l— Pedestal  Stand  Handle  and  Set  Screw  Complete. 
S-355-L— Pedestal  Stand. 


PflM 


322  MOTION     PICTURE     PROJECTION 


S-3I5-M 


P-3 


PLATE  16 


MOTION     PICTURE     PROJECTION  323 


SIMPLEX  PARTS 
(REWINDER) 

Name 

"M"— Rewinder  Bracket  Complete. 
S-438-M— Rewinder  Set  Screw. 
G-114-M— Rewinder  Spur  Gear. 

M-3 — Rewinder  Handle. 
N-108-M— Internal  Gear  Shaft  Nut. 

M-l— Internal  Gear  &  Shaft  (Includes  C-128-M,  S-438-M.) 

M-6— Rewinder  Reel  Shaft  and  Locks. 
C-128-M— Internal  Gear  Shaft  Collar. 
B-120-M— Rewinder  Bracket. 
S-315-M — Rewinder  Fastening  Screw  Shoe. 

P-3 — Rewinder  Fastening  Screw  Complete. 


324 


MOTION     PICTURE     PROJECTION 


R-142 

F-I09-Q 

S-522-Q 


*-i4i-Q 


PLATE  17 


Name 

C-1T5-Q— Collar  for  %"  Shaft. 

G-128-Q— Spiral  Gear  for  %"  Shaft. 

S-398-Q — Contact  Piece  Connection  Screw. 

P-224-Q— Contact  Piece  for  Top  Carbon. 

R-143-Q—  Upper  Carbon  Secondary  Guide  Rod. 

C-173-Q — Upper  Carbon  Clamp. 

J-101-Q — Upper  Carbon  Jaw. 

F-113-Q — Upper  Carbon  Secondary   Sliding  Frame. 


MOTION     PICTURE     PROJECTION  325 


F-112-Q — Upper  Carbon  Main  Sliding  Frame. 

S-218-L— Set  Screw. 

R-144-Q — Upper  and  Lower  Carbon  Frame  Guide  Rod. 

W-139-Q— Insulating  Washer. 

N-130-Q— Upper  Carbon  Contact  Piece  Retain  Nut. 

P-223-Q — Contact  Piece  for  Lower  Carbon. 

C-172-Q — Lower  Carbon  Clamp. 

J-100-Q— Lower  Carbon  Jaw. 

F-108-Q— Lower  Carbon  Secondary  Sliding  Frame. 

R-174-Q— Lower  Carbon  Cross  Feed  Sliding  Rod. 

F-104-Q — Burner  Cross  Feed  Sliding  Frame. 

S-394-Q— Carbon  Feed  Screw. 

B-139-Q— Burner  Base. 

S-218-Q— Headless  Set  Screw. 

R-142-Q— Main  Sliding  Frame  Guide  Rod. 

PM09-Q — Lower  Frame  Casting  of  3rd  Sliding  Frame. 

S-522-Q— Screw  for  Vertical  Adjustment  of  Arc. 

S-414-Q— Driving  Shaft  in  Top  Frame. 

P-261-Q— Universal  Joint  Cotter  Pin. 

J-102-Q— Universal  Joint. 

R-171-Q— Universal  Joint  Rivot. 

R-138-Q— Handle  Rod  10". 

R-144t-Q — Upper  and  Lower  Carbon  Frame  Guide  Rod. 

F-114-Q— Top   Frame  Casting  of  3rd  Sliding   Frame. 

S-523-Q — Screw  for  Top  Carbon  Longitudinal  Adjustment. 

C-175-Q — Screw  for  Top  Carbon  Longitudinal  Adjustment. 

C-175-Q— Collar  for  %"  Shaft. 

J-102-Q— Universal  Joint. 

G-128-Q— Spiral  Gear  for  %"  Shaft. 

R-137-Q— Handle  Rod  9". 

S-411-Q— Driving  Shaft  in   Lower   Carbon   Frame. 

R-138-Q— -Handle  Rod  10". 

S-218-L — Set  Screw. 

R-136-Q—  Handle  Rod  8". 

R-174-Q— Lower  Carbon  Cross   Feed   Sliding  Rod. 

R-139-Q— Handle  Rod  10M>". 

S-412-Q— Driving  Shaft  in   Lower   Carbon   Frame. 

C-175-Q— Collar  for   %"  Shaft. 

Q-16 — Horizontal  Longitudinal  Adjustment  of  Arc  Screw. 
C-176-Q— Collar  for  %"  Shaft. 

S-521-Q — Screw  for  Crosswise   Adjustment  of  Arc. 
F-110-Q— Main  Sliding  Frame. 
R-141-Q— Main  Cross  Feed  Sliding  Rod. 


326 


MOTION    PICTURE    PROJECTION 


<?    c» 

£    8 


00000  000  CO   O 

^-   2   <N   co  <b  0>        COJL  n  u, 

2$8*?  a      $2  S!C: 

Z    O)    CO    O    CD  O         O.Z  Q.    U 


MOTION     PICTURE     PROJECTION  327 


SIMPLEX  PARTS 
(ARC  LAMP) 

Name 

R-144-Q—  Upper  and  Lower  Carbon  Frame  Guide  Rod. 

H-138-Q— Large  Fibre  Handle. 

H-139-Q— Small  Fibre  Handle. 

G-129-Q— Spiral  Gear  for  %"  Shaft. 

G-128-Q— Spiral  Gear  for  %"  Shaft. 

F-103-Q— Handle  Flange. 

S-398-Q— Contact  Piece  Connection  Screw. 

N-130-Q— Upper  Carbon  Contact  Piece  Retain  Nut. 

N-131-Q— Upper  Carbon  Clamp  Nut. 

S-394-Q— Carbon  Feed  Screw. 

S-522-Q— Vertical  Adjustment  of  Arc  Screw. 

G-128-Q— Spiral  Gear  for   %"  Shaft. 

B-196-Q— Carbon  Jaw  Bolt. 

G-129-Q— Spiral  Gear   for   y2"  Shaft. 

P-228-Q— Lower  Carbon  Stop  Pin. 

N-141-Q— Lower  Carbon  Clamp  Nut. 

P-123-B— Taper  Pin. 

C-175-Q— Collar  for  %"  Shaft. 


328  MOTION     PICTURE     PROJECTION 


N-II8-F 


S-I86-F 


L-I02-F 


PLATE  19 


MOTION     PICTURE     PROJECTION  329 


:  SIMPLEX  PARTS 

(ARC  LAMP) 

Name 

N-118-F— Carbon  Feed  Bracket  Support  Screw  Nut. 
L-102-F — Carbon  Jaw  Tilt  Screw  Lever. 
S-186-F— Lower  Carbon  Holder  Wing  Screw. 


330 


MOTION     PICTURE     PROJECTION 


C-I97-F 
W-I53-F 
R-I72-F 
C-227-F 
B-I70-F 
S-555-F 
W-III-F 
B-M5-F 


PLATE  20 


S-113-F— Carbon  Holder  Clamp  Screw. 

W-101-F— Carbon  Holder  Washer. 

S-148-F— Set  Screw. 

B-114-F— Carbon  Holder  Bracket. 

P-245-F— Upper  Carbon  Tilt  Screw  Cotter  Pin. 

B-152-F— Upper  Carbon  Feed  Rack  (Sub-Bracket). 

F-9 — Upper  Carbon  Feed  Rack  Support. 

F-4 — Upper  Carbon  Feed  Rack  Bracket  Adjusting  Screw. 
J-103-F— Upper  Carbon  Tilt  Screw  Universal  Joint. 

N-4— Feed  Knob. 
S-164-A — Tension  Spring  Screw. 
S-335-F — Lamp  Adjusting  Gear  Friction  Spring. 
S-452-F— Upper  Carbon  Tilt  Screw  Adjusting  Shaft. 

N-4— Feed  Knob.      - 
S-127-N— Feed  Knob  Hub  Screw. 


MOTION     PICTURE     PROJECTION  331 


N-2— Carbon  Feed  Bracket  Tilt  Screw  Knob. 

F-5— Carbon  Feed  Bracket  Tilt  Screw. 

F-7 — Carbon  Feed  Bracket  Support. 

N-3— Feed  Knob. 

N-l— Feed  Knob. 

F-l— Carbon  Feed  Gear  and  Shaft. 
S-556-F— Lamp  Lateral  Screw  Shaft. 

N-l— Feed  Knob. 

N-3— Feed  Knob. 
S-516-F — Lamp  Carriage  Screw. 
S-290-F— Lamp  Adjusting  Gear  Shaft. 
S-113-F— Carbon  Holder  Clamp  Screw. 

F-2 — Lamp  Adjusting  Bracket  Plate  and  Pins. 
S-164-A — Lamp  Adjusting  Friction  Spring  Screw. 
P-lll-F— Carbon  Holder  Pin. 

F-10— Upper  Carbon  Holder. 
L-128-F— Carbon  Jaw  Tilt  Screw  Lever. 
S-439-F— Upper  Carbon  Jaw  Tilt  Screw. 
P-245-F— Upper  Carbon  Tilt  Screw  Cotter  Pin. 
B-113-F— Carbon  Feed  Bracket. 
P-199-F— Carbon  Feed  Bracket  Plate. 
S-103-F— Carbon  Feed  Bracket  Plate  Screw. 
S-110-F— Carbon  Feed  Bracket  Support  Screw. 
H-100-F— Carbon  Jaw  Tilt  Screw  Handle. 
S-148-F— Set  Screw. 
S-H4-F— Carbon  Jaw  Tilt  Screw. 
S-186-F— Lower  Carbon  Holder  Wing  Screw. 

F-12— Carbon  Holder  Bracket. 
W-102-F— Carbon  Holder  Mica  Washer. 
W-123-F— Upper  Carbon  Feed  Rack  Sub-Bracket  Washer. 
S-112-F— Carbon  Holder  Bracket  Screw. 

F-l  1— Lower  Carbon  Holder. 
WM01-F— Carbon  Holder  Washer. 
S-113-F— Carbon  Holder  Clamp  Screw. 
M-100-F— Carbon  Holder  Sheet  Mica. 

F-8— Lower  Carbon  Feed  Rack  Bracket. 
S-438-M— Set  Screw. 
C-197-F— Lamp  Carriage  Screw  Collar. 
W-153-F— Lamp  Carriage  Screw  Washer. 
R-172-F— Lamp  Carriage  Guide  Rod. 
C-227-F— Lamp  Carriage. 
B-170-F— Burner  Support  Bracket. 
S-555-F— -Lamp  Adjusting  Plate  Tension  Spring. 
W-lll-F— Lamp  Adjusting  Plate  Washer. 
B-115-F— Lamp  Adjusting  Bracket. 


332 


MOTION     PICTURE     PROJECTION 


DYNAMOS 

A  dynamo  electric  machine  is  a  device  for  convert- 
ing mechanical  energy  into  electric  energy.  The  word 
dynamo  is  generally  understood  to  mean  a  machine 
for  converting  mechanical  energy  into  electrical  en- 
ergy, and  the  word  motor  means  a  machine  for  con- 
verting electric  energy  into  mechanical  energy,  the 
essential  parts  of  a  dynamo  and  motor  are  the  same, 
namely — the  armature  and  field  magnet. 

Dynamos  are  divided  into  two  general  classes,  ac- 
cording to  the  character  of  the  current  they  deliver. 
A  direct  current  dynamo  delivering  a  current  that 
always  flows  in  one  direction,  that  is,  the  current 
never  reverses,  though  it  may  change  in  value  or 
pulsate. 

Alternating  current  dynamos  or  alternators,  de- 


100  K.W.  Engine-Type  Generator  and  Automatic  High- 
Speed  Engine 


MOTION     PICTURE     PROJECTION 


liver  a  current  that  periodically  reverses  its  direction 
of  flow,  the  number  of  reversals  per  second  depending 
on  the  number  of  poles  in  the  dynamo  and  on  the 
speed  of  rotation. 

A  direct  current  dynamo  usually  consists  of  a  se- 
ries of  conductors  arranged  on  the  surface  of  a 
cylindrical  iron  core  or  in  slots  near  the  surface,  the 
conductors  in  most  cases  being  parallel  with  the  axis 
of  the  core. 

The  core  is  mounted  on  a  shaft  that  is  supported 
on  bearings  so  that  the  armature  can  be  rotated  near 
the  pole  faces  of  a  field  magnet.  This  magnet  is 
excited  by  one  or  more  field  coils.  Any  even  number 
of  poles  may  be  used  according  to  the  size  and  type 
of  machine. 

The  principal  parts  of  a  dynamo  are:  armature 
core,  bands  on  armature  core,  commutator,  shaft, 
field  coils,  pole  faces,  brushes,  rear  end  bearing,  front 
end  bearing,  rear  end  journal,  front  end  journal,  ter- 
minal block  and  bedplate. 


LINE  PUSES 
ISAM  PS.  TOR  1 10  VOLTS 
10     •         •   220    - 

5     -         -  550 


CURRENT  AT  ARC 
IS  ADJUSTABLE 

FROM  2O  TO 


334  MOTION     PICTURE     PROJECTION 


FORT  WAYNE  A.  C.  TO  D.  C.  COMPENSARCS 

The  A.  C.  to  the  D.  C.  Compensarcs  is  what  is 
commonly  known  as  a  motor  generator  set,  that  is, 
two  machines,  a  generator  and  a  motor  coupled 
together  and  mounted  on  a  common  base. 

The  sets  are  shipped  -completely  assembled  and 
require  only  proper  installation,  filling  of  the  bear- 
ings with  oil  and  proper  connections  to  the  supply 
and  lamp  circuits  before  putting  into  service.  It 
should  be  understood  that  these  compensarcs  are 
special  machines  for  use  only  on  picture  projection 
arcs  and  cannot  be  used  for  ordinary  constant  volt- 
age purposes. 

The  complete  equipment  consists  of  the  A.  C.  to 
D.  C.  compensarc  proper,  two  short-circuiting 
switches,  one  for  each  picture  machine,  and  the 
panel  on  which  is  mounted  the  instrument  and  field 
control  rheostat.  All  single-phase  outfits  are 
equipped  with  proper  starter;  for  the  larger  multi- 
phase outfits  a  starting  compensator  is  furnished. 

The  A.  C.  to  D.  C.  Compensarc  should  be  installed 
in  a  clean,  dry,  well  ventilated  location,  and,  if  pos- 
sible, near  to  the  lamps  which  it  is  to  operate.  Often- 
times a  small  room  adjoining  the  projection  room  is 
provided  for  the  Compensarc ;  but  in  some  cases 
where  such  arrangements  cannot  be  made  the  machine 
is  installed  in  the  basement  of  the  theatre.  Inacces- 
sible locations  should  be  avoided,  as  such  locations 
will  result  in  the  machines  being  neglected,  allowed 
to  become  dirty  and  perhaps  damaged. 

It  is  not  necessary  to  provide  foundations  for  these 


MOTION     PICTURE     PROJECTION 


compensarcs,  but  the  floor  on  which  they  are  placed 
should  be  firm  and  free  from  vibration. 

The  machines  are  clamped  to  a  pair  of  wooden 
skids,    which    form    a    foundation    for    the    boxing. 


A.  C.  TO  D.  C.  COMPENSARC 


.LINE. 
3  PHASE 


BACK  OF  BOQRD. 


Fig.  1 
Connection  Diagram  for  35-Ampere  Lamp  Outfit 


MOTION     PICTURE     PROJECTION 


The  machine  should  if  possible  be  left  attached 
to  these  skids  until  it  has  been  conveyed  to  the  loca- 
tion which  it  is  finally  to  occupy.  It  is  preferable 
that  all  wiring  should  be  done  before  the  boxing  is 
removed  from  the  machine,  as  the  boxing  will  be 
effective  in  keeping  the  machine  clean. 

As  soon  as  the  machine  is  unboxed,  the  name  plate 
should  be  inspected  to  see  that  the  volts,  cycles  and 
phases  marked  on  the  name  plate  of  the  motor  agree 
with  those  of  the  circuit  on  which  the  machine  is  to 
be  used.  The  name  of  the  generator  marking  also 
indicates  the  volts  and  amperes  which  the  generator 
is  designed  to  deliver,  and  the  rating  should  agree 
with  that  specified  on  the  order.  It  should  be  re- 
membered that  the  direct-current  arc  for  motion 
picture  projection  requires  less  current  than  the 
alternating-current  arc,  25  to  35  amperes  at  55  volts 
being  usual  for  the  D.  C.  arc,  corresponding  to  40 
to  60  amperes  at  35  volts  for  the  alternating-current 
arc. 

The  A.  C.  to  D.  C.  Compensarc  should  be  run 
only  on  circuits  where  the  variation  of  either  fre- 
quency or  voltage  from  normal  does  not  exceed  five 
per  cent.  Where  both  frequency  and  voltage  vary, 
the  sum  of  the  variation  must  not  exceed  eight  per 
cent. 

If  for  any  reason  the  generator  or  motor  must  be 
taken  from  the  base  in  order  to  install  the  com- 
pensarc,  great  care  should  be  exercised  that  the 
machines  are  properly  lined  to  give  a  uniform  air 
gap  when  the  compensarc  is  reassembled.  If  this 
is  not  done,  trouble  will  occur  due  to  the  set  being 
out  of  line.  Dowell  pins  are  provided  on  the  gen- 


MOTION    PICTURE     PROJECTION 


337 


erator  end.  To  remove  these  hold  the  squared  head 
of  the  pin  with  a  wrench  and  tighten  up  the  nut 
which  will  pull  out  the  pin.  Be  careful  that  any 
liners  found  under  the  feet  are  carefully  replaced 


LINE 
3  PHASE 


A.  C.  TO  D.  C.  COMPENSARCS 

VIE  *V  FROM 
BACK  OF  BOARD 


Fig.  2 
Connection  Diagram  for  the  50  and  the  70-Ampere  Lamp  Outfit 


338  MOTION     PICTURE     PROJECTION 

in  their  proper  place.  Should  the  coupling  be 
taken  apart,  it  must  be  assembled  carefully,  making 
sure  that  the  halves  fit  properly. 

Diagram  Fig.  1  shows  the  external  connections 
for  the  35  amperes  two-lamp  series  outfit.  Fig.  2 
shows  the  external  connections  for  the  50  and  70- 
ampere  two-lamp  series  outfit,  using  only  a  switch 
between  the  line  and  the  motor  end  of  the  machine 
on  the  two-phase  and  three-phase  circuits.  The  use 
of  a  double  throw  switch  having  one  side  fused  for 
running  and  the  other  unfused  for  starting  is  gen- 
erally acceptable  to  the  power  companies  for  motors 
of  five  horse-power  and  smaller.  If  the  power  com- 
panies or  the  local  conditions  require  a  starting 
compensarc,  the  motor  end  of  the  two  and  three- 
phase  compensarc  should  be  connected  to  the  line 
in  accordance  with  the  diagrams  Fig.  3  and  Fig.  4 
respectively. 

The  wiring  should  be  of  sufficient  size  so  that  the 
line  drop  from  the  machine  to  the  lamp  will  not 
exceed  one  volt,  or  two  per  cent  of  the  voltage  when 
the  machine  is  delivering  full-load  current  to  the 
lamp.  If  too  small  a  wire  is  used  the  lamp  will  be 
robbed  of  some  of  its  voltage  and  give  poor  light. 
The  lamp  side  of  these  machines  does  not  require 
fuses,  as  the  generators  are  so  constructed  that  they 
will  protect  themselves  against  overload  current 
when  the  arcs  are  short  circuited.  The  motor  side 
of  the  various  machines  should  be  fused  as  follows: 


MOTION     PICTURE     PROJECTION 


339 


Two 

Two 

Two 

35-ampere 
Lamps 

50-ampere 
Lamps 

70-ampere 
Lamps 

Alternately 

Alternately 

Alternately 

Fuses 

Fuses 

Fuses 

Single-phase   110-  volt.  .    . 
Single-phase   220-  volt  .  .    . 
Two-phase      110-  volt.  .    . 
Two-phase      220-  volt  .  .    . 
Three-phase    110-  volt.  .    . 
Three-phase    220-volt..    . 

80-ampere 
40-ampere 
40-ampere 
20-ampere 
50-ampere 
25-ampere 

100-  ampere 
50-ampere 
60-ampere 
30-ampere 
75-ampere 
35-ampere 

120-ampere 
60-ampere 
70-ampere 
35-ampere 
80-ampere 
40-ampere 

A.  C.  TO  D.  C.  COMPENSARCS 


Fig.  3 
Connections  of  Motor  End  of  A.  C.  to  D.  C. 

Compensarc  When  Compensator  Is  Used  on  Three-phase 
Circuits 


340  MOTION     PICTURE     PROJECTION 

Before  starting  the  set  see  that  it  is  perfectly  clean 
and  that  the  brushes  move  freely  in  their  holders  and 
make  good  contact  with  the  commutator.  Be  sure 
that  the  oil  wells  are  clean  and  filled.  These  ma- 
chines have  overflow  gauges  with  hinged  caps.  The 
oil  wells  should  be  filled  through  the  overflow  gauges 
rather  than  through  the  hinged  covers  in  the  bear- 
ings. This  method  will  prevent  waste  and  annoyance 
from  overflowing  of  the  oil  reservoirs.  Pour  in 
enough  oil  to  show  in  the  gauges,  the  thin  oil  fur- 
nished for  the  moving  picture  machine,  sewing  ma- 
chine oil  and  similar  light  oils  are  not  heavy  enough. 
It  is  better  to  purchase  a  can  of  "light  dynamo  oil" 
and  keep  it  for  the  compensarc. 

See  that  the  armature  turns  freely  in  the  bearings 
and  that  the  machine  is  level. 

Make  sure  that  all  the  connections  are  tight  and 
correspond  with  the  diagram  of  connections  for  the 
outfit  supplied. 

When  starting  up  see  that  the  armature  starts  to 
rotate  in  the  direction  marked  on  the  coupling.  The 
direction  of  rotation  of  two-phase  motors  can  be 
reversed  by  interchanging  two  line  leads  of  the  same 
phase.  In  the  case  of  single  and  three-phase  motors 
it  is  only  necessary  to  interchange  any  two  line  leads 
of  the  motor.  Immediately  after  starting,  see  that 
the  oil  rings  revolve  and  carry  the  oil  up  to  the  shaft. 
Always  keep  the  oil  at  the  proper  level  in  the  well, 
that  is,  nearly  to  the  lip  of  the  overflow  gauge. 


MOTION     PICTURE     PROJECTION 


341 


STARTING    THE     COMPENSARC 

In  starting  up  the  A.  C.  to  D.  C.  Compensarc, 
have  the  switches  at  the  lamps  open.  If  a  single- 
phase  outfit,  close  the  main  switch  and  move  the 
starting  arm  on  the  starting  box  from  the  "off" 
position  to  the  split  segment  which  will  introduce 
the  necessary  starting  coils  to  cause  the  armature 
to  start  to  rotate.  When  the  armature  has  attained 
nearly  full  speed,  the  starting  arm  should  be  moved 
quicldy  over  to  the' last  segment  where  it  is  held  by 
a  latch  controlled  by  a  relay  magnet.  If  the  voltage 
fails,  the  relay  magnet  will  release  the  latch,  allow- 


A.  C.  TO  D.  C.  COMPENSARCS 


Fig.  4 

Connections  of  Motor  End  of  A.  C.  to  D.  C.  Compensarc  When 
Compensator  Is  used  on  Two-phase  Circuits 


342  MOTION     PICTURE     PROJECTION 

ing  the  starting  arm  to  automatically  return  to  the 
"off"  position  stopping  the  motor. 

The  arm  of  the  starting  box  should  never  be  left 
in  starting  position  longer  than  one  minute,  usually 
much  less  time  will  suffice.  When  the  power  com- 
panies do  not  require  the  use  of  starting  compensa- 
tors in  connection  with  the  two  and  three-phase  out- 
fits they  should  be  equipped  with  double-throw  start- 
ing switches  which  have  only  one  side  fused. 

When  starting  up,  the  switch  should  be  closed 
to  the  unfused  side.  When  the  speed  of  the  arma- 
ture is  up  to  normal  the  switch  should  be  quickly 
changed  to  the  running  side  (fused  side). 

To  start  up  an  A.  C.  to  D.  C.  Compensarc  where 
a  starting  compensator  is  used,  see  that  compensator 
arm  is  in  the  "off"  position  and  close  the  main  switch. 
The  compensator  should  be  thrown  into  the  starting 
position  with  a  quick,  firm  thrust  and  held  there  until 
the  machine  comes  up  to  speed  (about  20  or  30 
seconds),  and  then  with  one  quick  firm  movement  the 
arm  should  be  pulled  over  into  the  running  position, 
where  it  is  held  by  a  lever  engaging  with  the  low- 
voltage  release  mechanism. 

Never,  in  any  case,  should  the  motor  be  started 
by  "touching,"  that  is,  by  throwing  the  starting  arm 
into  the  starting  position  and  quickly  pulling  it  out 
a  number  of  times.  Such  a  plan  of  "touching"  does 
not  make  the  rush  of  current  at  starting  less,  but,  on 
the  contrary,  it  produces  a  number  of  successive 
rushes  in  place  of  the  one  which  it  has  been  attempted 
to  avoid,  and,  what  is  often  a  more  serious  matter, 
causes  the  contact  fingers  to  be  so  badly  burned  that 
it  is  necessary  to  replace  them.  To  stop  the  ma- 


MOTION    PICTURE     PROJECTION  343 

chine  open  the  main  switch.  The  compensator  arm 
should  automatically  return  to  the  "off"  position 
on  the  opening  of  the  main  switch;  if  it  does  not, 
throw  it  over  to  the  "off"  position  by  hand. 

STARTING  FIRST  LAMP 

When  the  speed  of  the  machine  is  up  to  normal 
and  the  starting  box  or  switch  is  in  running  position 
and  the  rheostat  handle  set  as  marked  by  the  white 
arrow,  short-circuit  the  one  lamp  by  means  of  its 
short-circuiting  switch.  Then  close  the  lamp  switch 
and  bring  the  carbons  together  so  that  they  barely 
touch;  then  separate  them  about  1-16  of  an  inch, 
gradually  increasing  the  separation  as  carbons  heat 
up  until  the  proper  length  of  arc  is  reached.  The 
D.  C.  arc  should  be  from  5-16  to  3-8  of  an  inch 
long  or  about  twice  as  long  as  an  A.  C.  arc.  Adjust 
the  generator  field  rheostat  until  the  proper  amount 
of  current  is  flowing.  If  the  carbons  are  held  to- 
gether too  long  the  machine  voltage  will  be  auto- 
matically reduced  to  zero,  so  that  the  arc  will  not 
have  sufficient  voltage,  and  will  therefor  break  when 
the  carbons  are  separated.  Should  this  occur,  keep 
the  carbons  apart  about  10  seconds  until  the  machine 
voltage  can  automatically  build  up  again,  then  strike 
the  arc  as  directed  above. 

The  switchboard  panel,  having  instruments  mount- 
ed on  it  along  with  the  field  rheostat,  is  very  useful, 
and  the  proper  current  can  at  all  times  be  accurately 
maintained.  As  the  machine  warms  up,  the  handle  of 
the  rheostat  may  have  to  be  moved  one  or  two  but- 
tons from  the  mark  to  maintain  the  desired  voltage 
and  current.  If  the  circuits  are  all  connected  as 


344  MOTION     PICTURE     PROJECTION 

shown  in  the  diagram,  the  polarity  should  be  as  in- 
dicated, the  upper  carbon  being  positive.  Should 
the  upper  carbon  be  negative  and  the  instrument  on 
the  panel  board  read  backward,  the  trouble  must  be 
corrected.  See  that  all  connections  are  made  as 
indicated  on  the  diagram.  The  polarity  must  come 
correct  if  the  connections  are  made  in  accordance 
with  the  diagram  of  connections,  and  the  armature 
of  the  set  rotates  in  the  direction  marked  on  the 
coupling. 

STARTING    THE    SECOND    LAMP 

To  start  the  second  lamp,  bring  the  carbons  to- 
gether to  close  the  circuits ;  close  the  lamp  switch 
and  open  the  short-circuiting  switch.  This  puts  the 
two  lamps  in  series,  the  current  from  the  first  lamp 
flowing  through  the  second  lamp.  The  arc  at  the 
second  lamp  is  adjusted  in  the  regular  manner  while 
both  lamps  are  burning.  When  ready  to  change 
over  from  one  lamp  to  the  other,  bring  the  carbons 
of  the  first  lamp  together  and  close  its  short-circuit- 
ing switch,  continuing  the  projection  on  the  second 
lamp. 

It  has  been  found  in  practice  that  the  following 
scheme  gives  the  most  satisfactory  results.  A  minute 
or  two  before  the  end  of  a  reel  of  film  is  reached 
bring  the  carbons  of  the  second  lamp  together,  close 
its  line  switch  and  open  its  short-circuiting  switch. 
The  current  for  the  first  lamp  flowing  through  the 
carbons  of  the  second  lamp  causes  the  tips  of  the 
carbons  of  the  second  lamp  to  heat  up  to  a  white 
heat  without  actually  drawing  an  arc.  Since  the 
tips  of  the  carbons  are  heated  up  by  this  method  a 


MOTION     PICTURE     PROJECTION  345 

normal  arc  is  easily  and  quickly  secured  when  it  is 
time  to  change  over  to  the  second  lamp. 

Care  must  be  taken  that  the  two  lamps  are  not 
both  burning  any  longer  than  is  necessary,  as  the 
Compensarc  is  not  intended  to  carry  both  lamps 
continuously.  The  ammeter  on  the  panel  will  show 
the  current  flowing  through  the  arc  when  either  one 


Fig.  5 
A.  C.  to  D.  C.  Compensarc 

or  both  lamps  are  burning.  The  voltage  is  auto- 
matically increased  by  the  machine  to  compensate 
for  the  increased  drop  due  to  the  second  lamp  and 
the  current  is  held  practically  constant. 

It  is  important  that  all  parts  of  the  machine  be 
kept  clean.  Oil  should  not  be  allowed  to  collect 
either  on  the  machine  or  on  the  floor  about  it,  and 
the  machine  should  as  far  as  possible  be  kept  free 


*46  MOTION'     PICTURE     PROJECTION 

from  dust.  When  the  coils  of  a  machine  are  allowed 
to  become  dirty  and  oil-soaked,  it  reduces  their  in- 
sulation strength  and  eventually  causes  them  to  burn 
out.  A  small  hand  bellows  will  be  found  convenient 
for  removing  the  dust  from  the  armature  windings. 

BEAiLS 

The  oil-wells  should  occasionally  be  cleaned  and 
new  oil  supplied.  They  should  be  filled  through  the 
side  filling  hole,  and  not  through  the  top  of  the 
bearing,  for  if  filled  through  the  top  the  oil  is  likely 
to  flow  out  through  the  ends  of  the  bearings  into  the 
windings.  Only  good  grades  of  oil  free  from  dust  and 
sediment  should  be  used  for  poor  oil  or  oil  containing 
sediment  wfll  greatly  shorten  the  life  of  the  bear- 
ings. Immediately  after  starting  see  that  the  oil 
rings  revolve  freely  and  carry  the  oil  to  the  top  of 
the  shaft.  Keep  the  oil  at  the  proper  level  in  the 
well,  that  is,  nearly  to  the  lip  of  the  overflow  gauge. 
As  soon  as  the  bearing  linings  become  so  worn  that 
the  rotor  is  in  danger  of  rubbing  against  the  stator, 
a  new  set  of  linings  should  be  inserted.  To  remove 
the  bearings,  take  out-  the  set  screws  in  the  bearing 
housings,  lift  the  oil  rings  and  drive  out  the  bearings 
with  a  wooden  block  of  the  same  diameter  as  the 
bearings.  The  bearings  are  a  light  driving  fit  in  the 
housing  and  must  be  handled  carefully.  When  re- 
pair bearings  are  supplied  for  the  alternating  cur- 
rent motors  the  set  screw  depression  is  already  in  the 
bearing,  but  the  direct  current  bearings,  which  regu- 
late the  end  play,  are  supplied  without  being  pre- 
viously spotted.  They  must  be  spotted  before  being 
put  in  place,  using  a  3-16  inch  drill  and  spot- 


MOTION"     PICTURE     PROJECTION 


drilling  for  the  tip  of  the  set  screw  the  same  dis- 
tance from  the  end  of  the  bearing  as  is  the  bearing 
being  replaced. 

COMMUTATOR    AND    BEUSHES 

It  is  very  important  that  the  brashes  make  perfect 
contact  with  the  commutator,  and  to  secure  good 
contact  it  is  important  that  both  brashes  and  corn- 


Fig.  6 
Special  Cabinet  Panel  with  Ammeter  and  Fldd  Rheostat 

mutator  be  kept  clean  and  free  from  carbon  dost 
and  dirt. 

To  secure  proper  commutation  and  proper  opera- 
tion, the  brushes  must  occupy  the  correct  position 
on  the  commutator.  This  proper  position  of  the 
brush  yoke  has  been  determined  at  the  factory  while 
the  machine  was  on  test,  and  is  indicated  by  corre- 
sponding  chisel  marks  on  brush  yoke  and  frame. 
It  is  Terr  important  that  these  marks  indicated  by 


348 


MOTION     PICTURE     PROJECTION 


white  lead  should  be  in  line  to  secure  satisfactory 
operation  of  the  machine. 

If  the  brush  holders  should  become  loosened  or 
moved  in  any  way,  they  must  be  carefully  reset  so 
that  they  make  the  proper  angle  with  the  commuta- 
tor as  shown  in  Fig.  7.  They  must  also  be  so 
spaced  around  the  commutator  that  the  distance 
from  tip  to  tip  of  the  brushes  are  exactly  the  same. 
Care  should  be  taken  that  the  brush-holders  are 
securely  fastened  at  an  even  height  1-16  inch  above 
the  commutator. 

When  replacing  worn  down  brushes  the  new  ones 
should  be  fitted  to  the  commutator  by  means  of  fine 
sandpaper,  carefully  pulled  under,  the  brush  in  the 
direction  of  rotation,  being  held  tightly  to  the  con- 
tour of  the  commutator.  If  the  brushes  are  inspected 
once  a  week  and  all  gum  cleaned  away  from  the 
brushes  so  that  they  move  freely  in  the  brush-holders, 


Commutator 


Direction  of 
Rotat/on 


Fig.  7 
Showing  Correct  Method  of  Setting  the   Brushes 


MOTION     PICTURE     PROJECTION  349 

much  longer  life  of  brushes  and  commutator  will 
result.  If  the  pressure  is  too  heavy  the  wear  of 
both  brushes  and  commutator  will  be  excessive,  while 
if  the  pressure  is  too  light  the  contact  will  not  be 
properly  made  between  brushes  and  commutator  and 
sparking  may  result;  the  proper  pressure  of  the 
springs  on  the  brushes  is  just  sufficient  to  insure 
good  contact  between  brushes  and  commutator.  A 
dirty  commutator  can  be  best  cleaned  by  rubbing  with 
a  clean  cloth  saturated  with  kerosene  or  machine  oil. 
To  keep  the  commutator  in  good  condition,  wipe  it 
from  time  to  time  with  a  piece  of  canvas  lightly 
coated  with  sperm  or  machine  oil.  Lubricant  of  any 
kind  should  be  used  sparingly. 

If  the  commutator  begins  to  cause  trouble  at  any 
time,  due  to  roughness,  it  should  be  given  immediate 
attention.  Any  delay  will  aggravate  the  case  and 
may  result  in  undue  sparking,  heating  and  consequent 
troubles.  The  roughness  may  be  removed  by  polish- 
ing the  commutator  with  a  piece  of  very  fine  sand- 
paper by  pressing  it  against  the  surface  of  the  com- 
mutator with  a  block  of  wood  shaped  to  the  curva- 
ture of  the  commutator  face.  In  using  the  sandpaper 
(emery  cloth  should  never  be  used)  it  should  be  moved 
back  and  forth  along  the  surface  parallel  to  the  shaft 
to  prevent  grooving  the  face  of  the  commutator. 
When  sanding  is  finished,  the  commutator  surface 
and  brush  faces  must  be  wiped  carefully  to  remove 
any  copper  dust  and  grit  which  may  have  adhered 
to  them.  If  the  commutator  has  been  allowed  to 
become  very  rough  it  may  be  necessary  to  grind 
it  down  to  a  true  surface,  using  a  small  piece  of 
fine  sandstone.  In  using  this  it  should  be  steadied 


350  MOTION     PICTURE     PROJECTION 

against  the  brush  holders  (properly  protected)  or 
other  steady-rest.  Brushes  should  be  lifted  from  the 
commutator  while  grinding  it.  After  grinding  polish 
with  fine  sandpaper. 

If  the  above  treatment  does  not  remedy  the  trouble 
it  will  be  necessary  to  tighten  the  commutator  seg- 
ments and  turn  down  the  commutator.  The  com- 
mutator should  be  trued  by  taking  off  the  lightest 
cut  possible,  using  a  sharp  tool  and  high  cutting 
speed.  Following  the  operation  of  turning  down  the 
commutator,  the  mica  between  the  bars  should  be 
carefully  cut  down  below  the  surface  of  the  bars. 
Next  remove  the  tool  marks  from  the  surface  of  the 
commutator  with  very  fine  sandpaper,  and  blow  all 
the  copper  dust  and  chips  from  in  and  around  the 
commutator  bars,  making  a  final  inspection  to  see 
that  at  no  place  does  the  copper  dust  or  chips  bridge 
over  the  mica  from  one  bar  to  another.  The  truing 
of  the  commutator  should  be  required  only  after  a 
long  period  of  service,  if  the  machine  has  been  prop- 
erly cared  for,  and  should  be  done  only  by  someone 
familiar  with  such  work. 


MOTION     PICTURE     PROJECTION  351 


D.  C.  TO  D.  C.  MOTOR-GENERATOR  SET 

For  Projection  Arc  Control 
For  2  Arcs  in  Series  Used  Alternately 

GENERAL 

The  D.  C.  to  D.  C.  motor-generator  set  consists 
of  two  machines,  a  generator  and  a  motor,  coupled 
together  and  mounted  on  a  common  base. 

The  sets  are  shipped  completely  assembled  and 
require  only  proper  installation,  filling  of  the  bear- 
ings with  oil  and  proper  connection  to  the  supply 
and  lamp  circuits  before  putting  in  service.  Under- 
stand that  these  sets  are  special  machines  for  use 
only  on  picture  projection  arcs  and  cannot  be  used 
for  ordinary  constant  voltage  purposes. 

The  complete  equipment  consists  of  the  D.  C.  to 
D.  C.  motor-generator  set,  proper  starting  box,  two 
short-circuiting  switches  (one  for  each  picture  ma- 
chine) and  the  panel  on  which  is  mounted  the  am- 
meter and  field  control  rheostat. 

INSTALLATION 

Install  the  D.  C.  to  D.  C.  motor-generator  in  a 
clean,  dry,  well  ventilated  location  and,  if  possible, 
near  to  the  lamps  which  it  is  to  operate.  Oftentimes 
a  small  room  adjoining  the  projection  room  is  pro- 
vided for  the  set,  but  in  some  cases  where  such  ar- 
rangement cannot  be  made  the  machine  is  installed 
in  the  basement  of  the  theatre.  Avoid  inaccessible 
locations,  as  such  locations  will  result  in  the  ma- 
chines being  neglected,  allowed  to  become  dirty  and 
perhaps  damaged. 


352  MOTION     PICTURE     PROJECTION 

It  is  not  necessary  to  provide  foundations  for 
these  machines,  but  the  floor  on  which  they  are  placed 
must  be  firm  and  free  from  vibration. 


Fig.  2 
D.  C.  to  D.  C.  Motor-Generator  Set 

The  machines  are  shipped  clamped  to  a  pair  of 
wooden  skids  which  form  a  foundation  for  the  box- 
ing. If  possible,  leave  the  machine  attached  to  these 
skids  until  it  has  been  conveyed  to  the  location  which 
it  is  to  finally  occupy.  It  is  preferable  that  all  wir- 
ing should  be  done  before  the  boxing  is  removed 
from  the  machine,  as  the  boxing  will  be  effective  in 
keeping  the  machine  clean. 

As  soon  as  the  machine  is  unboxed,  inspect  the 
name  plate  to  see  that  the  volts  marked  on  the  name 
plate  of  the  motor  agree  with  those  of  the  circuit 
on  which  the  machine  is  to  be  used.  The  marking  of 
the  generator  name  plate  indicates  the  volts  and  am- 


MOTION     PICTURE     PROJECTION 


353 


peres  which  the  generator  is  designed  to  deliver  and 
this  rating  should  agree  with  that  specified  in  the 
order. 

CONNECTIONS 

Wiring  Diagrams 

Diagram  Fig.  8  shows  the  external  connections 
for  the  35-ampere  two-lamp  series  outfit  and  Fig.  9 
shows  the  external  connections  for  the  50,  70  and 
100-ampere  two-lamp  series  outfit. 

D.  C.  TO  D.  C.  MOTOR-GENERATOR  SETS 

V/ewFrom  Bock  of  Board 


Dtrect  Current 
L/ne 


To  Uoper  Carbon) 


Lamp  Shor 
Circuiting 

Switches 


Fig.  8 
Connection  Diagram  for  35-Ampfere  Lamp  Outfit 


354 


MOTION     PICTURE     PROJECTION 


Wiring 

Be  sure  that  the  wiring  is  of  sufficient  size  so  that 
tKe  line  drop  from  the  machine  to  the  lamp  will  not 
exceed  one  volt,  or  two  per  cent  of  the  voltage  when 
the  machine  is  delivering  full  load  current  to  the 
lamp.  If  too  small  a  wire  is  used  the  lamp  will  be 
robbed  of  some  of  its  voltage  and  give  poor  light. 

D.  C.  TO  D.  C.  MOTOR-GENERATOR  SETS 


Direct  Current 
Line 


To  UpperCarboi  • 
Lamp 


Fig.  9 
Connection  Diagram  for  the  50,  70  and  100-Ampere  Lamp  Outfit 


MOTION     PICTURE     PROJECTION 


355 


Fuses 

The  lamp  side  of  these  machines  does  not  require 
fuses,  as  the  generators  are  so  constructed  that  they 
will  protect  themselves  against  overload  current  when 
the  arcs  are  short  circuited. 

The  motor  side  of  the  various  machines  should  be 
fused  as  follows : 


Tw0> 
35-  ampere 
Lamps 
Alternately 

Two^ 
50-ampere 
Lamps 
Alternately 

Two^ 
TO-ampere 
Lamps 
Alternately 

Two 

100-ampere 
Lamps 
Alternately 

115  volts 
230  volts 
550  volts 

Fuses 
60-  ampere 
30-ampere 
15-ampere 

Fuses 
80-ampere 
40-ampere 
20-ampere 

Fuses 
120-  ampere 
60-ampere 
30-ampere 

Fuses 
160-ampere 
80-ampere 
40-ampere 

INITIAL  STARTING 

Before  starting  the  set  see  that  it  is  perfectly 
clean,  and  that  the  brushes  move  freely  in  their 
holders  and  make  good  contact  with  the  commutator. 

Be  sure  that  the  oil  wells  are  clean  and  filled. 
These  machines  have  overflow  gauges  with  hinged 
caps.  Fill  the  oil  wells  through  the  overflow  gauges 
rather  than  through  the  hinged  covers  in  the  bear- 
ings. This  method  will  prevent  waste  and  annoy- 
ance from  overfilling  of  the  oil  reservoirs. 

Pour  in  enough  oil  to  show  in  these  gauges.  The 
thin  oil  furnished  for  the  moving  picture  machines, 
sewing  machine  oil,  and  similar  light  oils  are  not 
heavy  enough;  it  is  better  to  purchase  a  can  of 
"light  dynamo  oil"  and  keep  it  for  the  motor-gen- 
erator. 

See  that  the  armature  turns  freely  in  the  bear- 
ings, and  that  the  machine  is  level. 


356  MOTION     PICTURE     PROJECTION 

Make  sure  that  all  connections  are  tight  and 
agree  with  the  diagram  of  connections  for  the  outfit 
supplied,  so  that  when  starting  up  the  armature  will 
start  to  rotate  in  the  direction  marked  on  the  coup- 
ling. 

Immediately  after  starting,  see  that  the  oil  rings 
revolve  freely  and  carry  the  oil  up  to  the  shaft. 
Always  keep  the  oil  at  the  proper  level  in  the  well, 
that  is,  nearly  to  the  lip  of  the  overflow  gauge. 

OPERATION 

Starting  the  Motor-Generator 

In  starting  up  the  D.  C.  to  D.  C.  set  have  the 
switches  at  the  lamps  open.  Close  the  main  line 
switch  and  move  the  lever  of  the  starting  box  to  the 
first  contact  point  holding  it  there  for  two  or  three 
seconds  to  allow  the  armature  to  start  to  rotate. 
Then  move  the  lever  slowly  over  the  remaining  con- 
tact points  until  it  reaches  the  running  position 
where  it  will  be  held  in  place  by  the  retaining  mag- 
net. If  the  voltage  fails  the  retaining  magnet  will 
release  the  latch  allowing  the  starting  arm  to  auto- 
matically return  to  the  "off"  position  stopping  the 
motor. 

To  stop  the  machine  open  the  main  switch.  The 
arm  of  the  starting  box  should  then  automatically 
return  to  the  "off"  position.  If  it  does  not,  throw 
it  over  to  the  "off"  position  by  hand. 

Starting  First  Lamp 

When  the  speed  of  the  machines  is  up  to  normal 
and  the  arm  of  the  starting  box  is  in  running  posi- 
tion and  the  rheostat  handle  set  as  marked  by  the 


MOTION    PICTURE     PROJECTION  357 

white  arrow,  short  circuit  the  one  lamp  by  means 
of  its  short-circuiting  switch.  Then  close  the  lamp 
switch  of  the  other  lamp  and  bring  the  carbons  to- 
gether so  that  they  barely  touch;  then  separate 
them  about  1/16  of  an  inch,  gradually  increasing 
the  separation  as  carbons  heat  up  until  proper 
length  of  arc  is  reached.  The  D.  C.  arc  should  be 
from  5/16  to  %  of  an  inch  long,  or  about  twice  as 
long  as  an  A.  C.  arc.  Adjust  the  generator  field 
rheostat  until  the  proper  amount  of  current  is  flow- 
ing. 

If  carbons  are  held  together  too  long,  the  machine 
voltage  will  be  automatically  reduced  to  zero,  so 
that  the  arc  will  not  have  sufficient  voltage  and 
will,  therefore,  break  when  carbons  are  separated. 
Should  this  occur,  keep  carbons  apart  about  10 
seconds  until  machine  voltage  can  automatically 
build  up  again ;  then  strike  the  arc  as  directed  above. 

The  switchboard  panel  has  an  ammeter  mounted 
on  it  along  with  the  field  rheostat  and  is  very  useful 
as  the  proper  current  can  at  all  times  be  accurately 
maintained.  As  the  machine  warms  up,  the  handle 
of  the  rheostat  may  have  to  be  moved  one  or  two 
buttons  from  the  mark  to  maintain  the  desired  volt- 
age and  current. 

If  the  circuits  are  all  connected  as  shown  in  the 
diagram  the  polarity  should  be  as  indicated.  The 
upper  carbon  must  be  positive.  Should  the  upper 
carbon  be  negative  and  the  instrument  on  the  panel 
read  backward,  the  trouble  must  be  corrected.  See 
that  all  connections  are  made  as  indicated  on  the 
diagram. 

The  polarity  must  come  correct  if  the  connections 


358  MOTION     PICTURE     PROJECTION 

are  made  in  accordance  with  the  diagram  of  con- 
nections and  the  armature  of  the  set  rotates  in  the 
direction  marked  on  the  coupling. 

Starting  the  Second  Lamp 

To  start  the  second  lamp  bring  the  carbons  to- 
gether to  close  the  circuit,  close  the  lamp  switch 
and  open  the  short-circuiting  switch.  This  puts 
the  two  lamps  in  series,  the  current  from  the  first 
lamp  flowing  through  the  second  lamp.  The  arc  at 
the  second  lamp  is  adjusted  in  the  regular  manner 
while  both  lamps  are  burning. 

When  ready  to  change  over  from  one  lamp  to  the 
other  bring  the  carbons  of  the  first  lamp  together 
and  close  its  short-circuiting  switch,  continuing  the 
projection  on  the  second  lamp. 

It  has  been  found  in  practice  that  the  following 
scheme  gives  the  most  satisfactory  results.  A  minute 
or  two  before  the  end  of  a  reel  of  film  is  reached 
bring  the  carbons  of  the  second  lamp  together,  close 
its  line  switch  and  open  its  short-circuiting  switch. 
The  current  for  the  first  lamp  flowing  through  the 
carbons  of  the  second  lamp  causes  the  tips  of  the 
carbons  of  the  second  lamp  tc  heat  up  to  a  white 
heat  at  the  tips  without  actually  drawing  an  arc. 
Since  the  tips  of  the  carbons  are  heated  up  by  this 
scheme  a  normal  arc  is  easily  and  quickly  secured 
when  it  is  time  to  change  over  to  this  second  lamp. 

Take  care  that  the  two  lamps  are  not  both  burn- 
ing any  longer  than  is  necessary,  as  the  motor- 
generator  is  not  intended  to  carry  both  lamps  con- 
tinuously. The  ammeter  on  the  panel  will  show  the 
current  flowing  through  the  arc  when  either  one  or 


MOTION     PICTURE     PROJECTION  359 

both  lamps  are  burning ;  the  voltage  is  automatically 
increased  by  the  machine  to  compensate  for  the  in- 
creased drop  due  to  the  second  lamp  and  the  cur- 
rent is  held  practically  constant. 


360 


MOTION     PICTURE     PROJECTION 


THE   TRANSVERTER 

The  Transverter  is  a  vertical  machine,  self-con- 
tained and  occupies  a  floor  space  of  less  than  two 
feet  square.  The  panel  carrying  the  switches  and 
meters  can  be  located  at  any  point  convenient  to 
the  operator,  while  the  machine  is  best  placed  near 
a  wall  anywhere  on  a  floor  not  subject  to  vibration, 
and  in  a  location  which  is  not  damp  and  which  af- 
fords ready  inspection. 

A  pair  of  steel  lugs  will  be  found  on  the  sides  of 
the  generator  frame.  After  the  machine  is  taken  out 


MOTION     PICTURE     PROJECTION  361 

of  the  crate,  it  can  be  very  conveniently  handled  by 
these  lugs,  should  it  be  necessary  to  lift  it  any  dis- 
tance to  its  permanent  location.  When  located,  it 
should  be  placed  upon  the  four  pieces  of  cork  com- 
position which  are  sent  with  the  machine,  and  which 
serve  to  minimize  vibration  and  at  the  same  time  in- 
sulate the  frame  from  ground.  It  is  not  necessarv 
to  bolt  it  down. 

Installation  Instructions 

Wiring — Make  connection  from  the  A.  C.  line  ser- 
vice to  the  starting  switch  and  from  the  starting 
switch  to  motor  terminals,  1,  2  and  3;  then  close  the 
switch  and  make  sure  that  the  armature  rotates  in 
the  direction  indicated  by  the  arrow  on  the  top  bear- 
ing housing.  If  the  armature  rotates  in  the  wrong 
direction,  it  must  be  reversed  by  interchanging  any 
two  of  the  A.  C.  motor  terminals. 

Caution — Do  not  change  connections  inside  of 
Transverter  unit  to  correct  direction  of  rotation  or 
polarity.  The  machines  are  all  checked  up  complete 
with  their  equipment  when  tested.  The  motor  must 
be  connected  to  proper  side  of  the  line  and  connec- 
tions to  panels  must  be  made  correctly  to  bring  po- 
larity of  the  instruments  and  lamp  carbons  correct. 

Fuses — Fuse  the  A.  C.  motor  side  of  these  ma- 
chines only.  The  D.  C.  Generator  circuit  does  not 
require  fuses  or  switches  other  than  shown  on  the 
wiring  print.  The  A.  C.  fuses  at  the  A.  C.  motor 
starting  switch  must  be  of  large  enough  capacity  to 
carry  the  maximum  load  of  the  machine. 

Wiring  to  Lamps — Use  wire  of  sufficient  size  to 
carry  rated  current  of  Transverter  to  connect  from 


362  MOTION     PICTURE     PROJECTION 

L  and  A  on  the  Transverter  to  panelboard  and 
lamps.  No.  14  or  No.  12  size  wire  may  also  be  used 
to  connect  F  on  Transverter  to  the  F  on  the  Field 
Regulator  in  panel  board. 

The  Transverter  is  a  motor  generator  with  the 
motor  below  and  the  generator  above,  the  two  being 
built  into  one  unit. 

The  shaft  of  the  generator  is  supported  at  its 
upper  end  in  a  radical  ball  bearing,  its  lower  end 
taking  half  of  a  coupling,  the  other  half  of  which  is 
located  at  the  top  of  the  motor  shaft.  The  shaft 
of  the  motor  is  supported  by  two  radical  ball  bear- 
ings, top  and  bottom,  and  a  ball  thrust,  which  takes 
the  combined  weight  of  both  rotor  and  armature. 

The  coupling  is  so  constructed  as  to  carry  a  cen- 
trifugal fan  which  provides  ventilation  from  above 
and  below,  discharging  the  air  out  of  openings  in 
the  side  of  the  unit. 

Grease  cups  are  provided  for  each  of  the  bearings, 
the  latter  being  enclosed  in  dust-proof  housings. 

The  driving  unit  is  a  simple,  two  or  three  phase 
induction  motor  of  ample  capacity,  running  very 
close  to  constant  speed  regardless  of  load. 

The  generator  is  of  the  constant  current  type. 
The  design  is  bipolar,  which  lends  itself  most  readily 
to  constant  current  characteristics  as  shown  in  the 
curve. 

The  field  winding  is  shunt  with  interpole  windings 
for  commutation.  The  brushes  and  interpoles  are  so 
positioned  relative  to  the  main  poles  as  to  get  a  prac- 
tically constant  current  over  a  wide  range  of  voltage, 
which,  in  the  double  arc  machine,  reaches  from  50  to 
approximately  115  volts.  The  position  of  the 


MOTION     PICTURE     PROJECTION  363 


Parts  Making  Up  the  Transverter 

brushes  on  the  commutator  should  never  be  shifted 
by  rocking  them,  as  this  will  change  the  entire  char- 
acterization of  the  machine.  If  any  sparking  de- 


364 


MOTION     PICTURE     PROJECTION 


WIR1/46  DIAeRA/^ 
of- 

ARC — 


CorKTMt 


velops,  it  is  due  rather  to  imperfect  brush  contact 
than  brush  position. 

Operating  Instructions 

Have  lamp  carbons  separated  and  lamp  switches 
open. 

Close  motor  starting  switch. 

Close  that  switch  which  controls  lamp  that  you  do 
not  wish  to  use. 

Permit  the  generator  voltage  to  build  up  before 
attempting  to  strike  the  arc,  then  strike  the  car- 
bons together  quickly  and  lightly,  separating  them 
immediately  to  about  1-16  of  an  inch,  gradually  in- 
creasing the  separation  as  the  carbons  heat  up  until 
a  proper  length  of  arc  is  reached.  ( Note :  55  volts 


MOTION    PICTURE     PROJECTION  365 

will  then  show  on  the  Voltmeter,  provided  proper  size 
carbons  are  used  and  they  are  set  at  correct  angle.) 

Adjust  for  amperes  desired  by  means  of  the  Field 
Regulator  in  panel.  (Note:  The  Regulator  pro- 
vides means  of  obtaining  more  amperage  from  the 
Transverter  than  its  rated  capacity.  This  greater 
amperage  should  not  be  used  continuously.  It  is  in- 
tended only  in  order  to  provide  for  very  dense  films 
or  colored  pictures.  Regulator  also  provides  means 
of  obtaining  less  amperage  than  the  rated  capacity 
of  the  machine,  thus  providing  for  films  that  do  not 
require  so  much  light.  If  the  operator  will  take  ad- 
vantage of  the  provisions  that  have  been  made  for 
obtaining  the  high  and  low  amperage,  he  will  im- 
prove the  projection  and  at  the  same  time  effect  a 
considerable  saving  in  the  projection  light  bills.) 

For  Obtaining  Two  Arcs  Simultaneously — Assum- 
ing that  one  arc  is  alreay  in  operation : 

Adjust  that  arc  to  about  a  55  volt  length; 
.  Bring  the  carbons  of  the  second  arc  lamp  to- 
gether and  while  in  that  position  open  the  switch 
controlling  that  lamp,  then  slowly  separate  the  car- 
bons to  about  1-16  of  an  inch,  gradually  increasing 
the  separation  as  the  carbons  heat  up  until  this 
second  lamp  also  has  a  55  volt  arc  length.  (Note: 
The  Voltmeter  on  the  panel  board  will  then  be  in- 
dicating combined  voltage  of  the  two  arcs.) 

To  discontinue  the  use  of  either  arc,  merely  close 
switch  controlling  that  lamp. 

Note:  If  operator  will  follow  the  above  instruc- 
tions carefully,  he  can  heat  up  the  carbons  in  the 
second  lamp  or  burn  in  a  new  trim  of  carbons  with- 
out disturbing  the  arc  of  the  other  lamp.  The  two 


MOTION     PICTURE     PROJECTION 


arcs  can  be  used  simultaneously  for  dissolving  the 
pictures. 


Phanton  View  of  Transverter 

General  Care 

Keep  the  machine  clean. 

Keep  the  commutator  clean  (but  do  not  use  sand 
or  emery  paper  on  it).  If  it  becomes  dirtyi  hold  a 
pad  of  coarse  canvas  or  cheese  cloth  against  its  sur- 
face while  running,  and  when  free  of  dirt  wipe  the 


MOTION     PICTURE     PROJECTION  367 

surface  with  a  clean  cloth  pad  that  is  slightly  moist- 
ened with  pure  vaseline. 

Do  not  permit  the  carbon  brushes  to  become  too 
short,  as  disastrous  sparking  will  result.  A  new  set 
of  carbon  brushes  should  be  put  in  before  the  old 
ones  are  completely  worn  out.  When  putting  in  new 
brushes  it  is  well  to  first  put  in  two,  one  in  each  hold- 
er at  opposite  ends  of  the  commutator,  then  as  soon 
as  they  are  worn  into  a  perfect  fit  to  the  surface  of 
the  commutator,  replace  the  remaining  old  brushes 
with  new  ones. 

The  machine  has  ball  bearings  and  they  require  a 
very  small  amount  of  lubrication. 

The  three  grease  cups  on  the  machine  should  each 
be  given  one  turn  twice  each  week.  If  this  is  done 
these  grease  cups  will  require  refilling  once  each 
thirty  to  forty  days. 

Note:  Refill  the  grease  cups  with  Transverter 
grease  only,  as  other  kinds  of  grease  will  be  likely  to 
injure  the  highly  polished  steel  balls  and  surfaces 
of  the  bearings. 

Troubles  and  Remedies 

If  the  brushes  are  not  replaced  as  explained  above, 
the  commutator  may  become  blackened  and  require 
attention  either  by  the  application  of  a  stone,  or,  in 
severe  cases,  it  may  require  the  removal  of  the  ar- 
mature so  as  to  turn  the  commutator  in  a  lathe. 

Should  the  bearings  become  dry  or  an  improper 
lubricant  be  used,  it  may  cause  the  destruction  of  a 
bearing  and  require  its  replacement. 

In  case  it  is  necessary  to  have  any  repair  parts  or 
supplies,  order  these  direct  from  the  factory,  giving 
the  serial  number  on  the  name  plate  of  the  machine. 


368 


MOTION     PICTURE     PROJECTION 


Connections    of   a   Double-Arc    Transverter,    with    Emergency 
Inductor  System 


MOTION     PICTURE     PROJECTION 


t-MOTO*  HINCMTOK  fUHCi.  FOR  3  AH  C  LAMPS 


Wiring  Diagram  For  Two  Motor  Generators  and  Control 
Switchboard,  Two  Projectors  and  One  Spotlight,  Permitting 
Single  or  Dual  Operation  of  Motor  Generators.  J.  E.  Robin. 


370 


MOTION     PICTURE     PROJECTION 


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EMERGENCY  PANEL 

FOR  THREE  ARC  LAMPS 

ON 
VOLTS  2  PHASE       CYCLE 


A.C  LINE 


B-S6 


NORTHWESTERN  ELECTRIC. CO.  CHIC.AOO.  ILLT      DESIGNERS  SrBUUPERS 


MOTION    PICTURE     PROJECTION 


371 


GENERTAOR  TROUBLES,  THEIR  CAUSES 
AND  REMEDY 

Methods  for  Locating  and  Repairing  Break  in  the 
Armature  of  Generator 

A  break  in  an  armature  must  be  located  by  the 
fall  of  potential  method,  which  means  that  a  current 
must  be  sent  through  the  armature  and  the  voltage 
tested  across  the  various  segments.  First  disconnect 
all  the  leads  from  the  armature  and  lift  all  brushes 
except  one  on  each  pole,  then  connect  the  battery  to 
these  brushes  through  the  resistance  and  ammeter 
shown  in  Fig.  1,  connect  the  detector  to  one  brush, 
and  then  to  each  segment  in  turn  with  a  wire  from 
the  other  terminal  of  detector  until  the  break  is  lo- 
cated. 


372  MOTION     PICTURE     PROJECTION 

If  the  two  wires  from  the  detector  are  connected 
to  the  segments  that  the  brushes  are  standing  on,  a 
deflection  will  be  seen  caused  by  a  fall  of  voltage 
through  the  coils.  If  we  gradually  draw  the  move- 
able  wire  over  the  segments  towards  the  other  brush, 
the  deflection  will  gradually  fall  to  zero,  providing 
it  is  on  the  side  on  which  the  break  does  not  occur 
(Fig.  1).  If,  however,  the  wire  is  drawn  over  the 
segments  on  the  other  side,  the  deflection  on  the  in- 
strument will  remain  constant  until  the  failing  seg- 
ment is  reached,  when  the  deflection  will  drop  to  zero 
as  the  wire  passes  over  the  break. 

Instead  of  moving  the  testing  wire  around  the 
commutator,  a  course  that  might  not  always  be  con- 
venient, it  could  be  held  stationary  against  the  com- 
mutator, say  a  few  segments  from  one  of  the  brushes, 
and  the  armature  gradually  pulled  around  till  the 
break  appeared. 

In  this  case  on  the  unbroken  side  a  constant  de- 
flectiqn  will  be  obtained  till  the  break  passes  a  brush, 
when  the  needle  will  fall  to  zero.  On  the  other  side 
there  will  be  no  deflection  till  the  break  passes  one  of 
the  brushes.  So  long  as  the  break  is  between  the 
movable  testing  wire  and  the  brushes  to  which  the 
detector  is  connected,  there  is  a  deflection;  but  not 
when  the  break  is  between  the  fire  brushes  and  the 
testing  wire.  If  the  instrument  gives  a  good  reading 
between  two  adjoining  segments,  it  will  show  a  much 
larger  reading  across  a  break. 

If  a  millivoltmeter  is  available,  the  matter  is  some- 
what simplified,  as  a  small  current  is  sufficient  for 
testing,  such  for  instance  as  the  current  taken  by  an 
incandescent  lamp.  If,  therefore,  the  armature  be 


MOTION     PICTURE     PROJECTION  373 

connected  to  a  source  of  supply  through  a  lamp,  a 
millivoltmeter  will  give  a  good  deflection  across  a 
break.  Millivoltmeter  is  the  instrument  used  as  a 
shunted  ammeter  in  conjunction  with  various  law 
resistances  called  shunts;  when  used  as  a  millivolt- 
meter  in  the  manner  above  described,  it  is  used  alone, 
the  armature  itself  taking  the  place  of  the  shunt 
(Fig.  2). 


LAMP 


FIG  £. 

Having  found  the  broken  section  it  must  be  exam- 
ined till  the  actual  break  is  discovered.  In  the  case 
of  a  winding,  the  bad  section  can  be  taken  out  and 
a  new  one  put  in  without  much  difficulty.  In  the 
case  of  a  formed  wound  drum,  it  is  generally  an 
inaccessable  bottom  wire  that  breaks.  In  this  case 
it  is  usual  to  strip  the  armature  till  the  break  is 
reached;  this  is  not  always  necessary.  Having 
found  tlfe  defective  section,  cut  out  as  much  as 
can  be  got  at,  that  is  the  conductors  on  the  surface 
of  the  core  or  in  the  slots.  Leave  the  end  crossing 
wires  in,  but  with  the  ends  separated  and  rewind  the 
section  with  the  end  crossings  on  top  of  the  others. 


374  MOTION    PICTURE     PROJECTION 

Overheating  the  Armature 

Several  causes  will  cause  overheating  of  the  ar- 
mature, the  most  common  being — overload,  grounds, 
eddy  currents  in  the  core,  eddy  currents  in  the  con- 
ductors, short-circuit  in  the  coils,  sparking  at  the 
commutator,  heat  conducted  from  the  bearings,  low 
insulation.  If  the  excessive  heating  is  uniform  over 
the  whole  armature,  the  machine  is  overloaded. 

Should  one  or  two ,  of  the  coils  be  overheated,  the 
trouble  is  due  to  a  short  circuit  in  the  winding.  If 
the  core  is  hotter  than  the  coils,  the  trouble  is  due  to 
excessive  eddy  currents  in  the  laminations,  caused  by 
the  core  rubbing  up  against  one  of  the  pole  faces,  or 
it  may  be  caused  by  a  number  of  the  laminations  being 
short-circuited,  the  slots  having  been  filed  too  much 
when  the  core  was  built.  Heating  due  to  eddy  cur- 
rents either  in  the  armature  core  or  the  conductors, 
cannot  be  remedied  by  the  projectionist,  the  maker 
of  the  machine  should  be  immediately  notified.  The 
test  is  to  run  the  generator  on  open  circuit  and  take 
note  of  the  rise  in  temperature.  To  test  for  a  ground 
in  the  windings,  first  disconnect  the  generator  from 
the  circuit,  and  then  run  it  up  ~to  normal  speed. 
Using  an  ordinary  test  lamp,  touch  the  opposite 
brushes  to  make  sure  you  have  the  voltage. 

Then  connect  the  lamp  terminals  between  the  gen- 
erator frame  and  the  poles.  Should  there  be  a 
ground  the  test  lamp  will  either  glow  or  light.  The 
cause  of  the  ground  should  then  be  located  and  re- 
moved. 


MOTION     PICTURE     PROJECTION  375 

Locating  Ground  Coil 

To  locate  a  grounded  coil  is  a  difficult  job,  and 
should  not  be  undertaken  by  anyone  who  is  not  fa- 
miliar with  electrical  apparatus. 

The  armature  should  be  removed  from  the  field 
and  set  on  trestle,  a  current  (not  to  exceed  the  nor- 
mal current  of  the  dynamo)  should  be  passed 
through  the -armature  from  any  one  of  the  commuta- 
tor segments  to  the  shaft.  A  compass  should  be  held 
near  the  conductors,  and  the  needle  will  be  deflected 
in  a  certain  direction  due  to  the  flow  of  current.  If 
the  armature  is  slowly  turned  round,  till  such  time 
as  the  compass  needle  reverses,  this  will  indicate  the 
proximity  of  the  grounded  coil. 

Low  insulance  (insulation  resistance)  between  the 
core  and  the  armature  winding,  is  generally  caused 
by  the  presence  of  moisture,  and  often  accompanied 
by  vapor  arising  from  the  armature.  This  can  be 
remedied  by  baking  the  armature  in  an  oven  at  a 
temperature  of  about  200°  F,  or  by  running  the  ma- 
chine unloaded  for  a  few  hours  and  sending  a  small 
current  round  the  windings. 

The  short  circuiting  of  the  coils  is  generally  ac- 
companied by  heavy  sparking  and  a  smell  of  burning 
may  be  caused  by  copper  dust,  oil  on  bits  of  solder 
lodged  between  the  commutator  arms. 

Locating  Short-Circuited  Coil 

To  locate  a  short-circuited  coil,  use  the  same 
method  to  locate  break  in  armature.  It  is  best  to 
test  between  each  pair  of  segments,  remembering 
that  the  readings  will  all  be  alike  when  connected 


376  MOTION     PICTURE     PROJECTION 

across  the  good  coils,  and  that  a  variation  in  the 
reading  points  to  a  fault. 

The  remedy  for  a  short  circuited  coil  is  to  strip 
the  damaged  parts  and  rewind. 

A  temporary  repair  job  can  be  accomplished  by 
disconnecting  the  short  circuited  coil  from  the  com- 
mutator arms,  and  then  bridging  the  arms,  thus  cut- 
ting out  the  defective  coil. 

Should  the  short  circuiting  of  the  coils  be  due  to 
copper  dust,  oil,  etc.,  between  the  commutator  arms, 
all  that  will  be  necessary  will  be  to  dislodge  the  for- 
eign substance. 

When  a  generator  is  overloaded,  the  temperature 
of  the  armature  will  rise,  and  heavy  sparking  of  the 
brushes  will  also  result.  If  the  machine  is  run  with- 
out removing  the  overload,  the  insulation  of  the  ar- 
mature may  be  destroyed. 

Overheated  Bearings 

A  hot  bearing  may  result  from  one  or  more  of  the 
following  causes:  Insufficient  lubrication,  faulty 
lubrication,  grit  or  other  foreign  matter  in  the  bear- 
ings ;  armature  not  centered  with  respect  to  pole 
pieces;  side  pull  due  to  magnetic  pull  on  armature; 
end  pressure  of  collar  against  the  bearing — due  to 
machine  being  out  of  line,  with  its  driving  shaft,  or 
to  want  of  alignment  in  engine;  to  a  bent  armature 
shaft ;  shaft  rough  or  cut,  etc.,  etc. 

Only  the  best  of  oil,  free  from  sediment  and  grit 
should  be  used  for  lubrication,  the  ordinary  machine 
oil  supplied  and  used  on  the  projector,  is  too  thin 
for  this  class  of  work,  all  the  oil  cups  should  be  kept 
clean  and  filled,  the  oil  rings  should  be  watched  to 
see  that  they  carry  the  oil  up  to  the  shaft. 


MOTION     PICTURE     PROJECTION  377 

When  the  heating  of  a  bearing  is  due  to  the  pres- 
ence of  dirt  or  grit,  it  should  be  cleaned  with  some 
thin  oil  or  kerosene.  If  kerosene  is  used  do  not  for- 
get to  use  a  good  lubricant  directly  after  the  cleans- 
ing. 

The  bearing  caps  should  just  be  tight  enough  to 
run  freely,  without  any  side  play.  If  a  bearing  is 
too  tight  the  oil  cannot  get  through  as  the  oil  passage 
remains  full.  The  same  thing  occurs  if  the  oil  pas- 
sages become  choked  with  dirt  or  grit. 

Do  not  tighten  up  the  bearing  caps  with  pliers,  as 
sufficient  pressure  can  be  brought  to  bear  with  the 
finger  and  thumb.  After  tightening  up  the  caps  the 
armature  should  revolve  freely,  and  when  in  motion 
the  armature  should  come  gradually  to  rest.  Should 
the  armature  stop  quickly  the  bearings  are  too  tight. 

A  bent  shaft  will  cause  the  armature  to  rub  pole 
pieces,  and  thus  produce  sparking,  vibration  and 
overheating.  To  overcome  this  it  will  be  necessary  to 
remove  the  armature  from  the  machine  and  have  the 
shaft  straightened  in  what  manner  is  most  handy. 
It  may  be  found  necessary  to  withdraw  the  shaft 
from  armature  before  this  can  be  accomplished. 

A  rough  shaft  may  be  caused  by  dirt,  grit  or  over- 
heating. The  roughness,  if  not  excessive,  can  be 
taken  out  by  the  use  of  a  little  emery  cloth,  but  care 
should  be  taken  to  remove  all  grit  and  filings  when 
the  job  is  finished.  If  the  roughness  is  so  great  that 
it  cannot  be  taken  out  with  the  use  of  emery  cloth, 
it  will  be  necessary  to  remove  the  armature,  and 
smooth  up  the  shaft  in  a  lathe,  using  a  very  fine  file 
and  emery  cloth. 


378  MOTION     PICTURE     PROJECTION 

Noise  in  a  generator  can  be  laid  to  one  of  the  fol- 
lowing causes :  Bent  or  broken  shaft ;  armature  out 
of  balance ;  brushes  grinding  commutator ;  armature 
hitting  pole  pieces ;  loose  bearings.  All  screws  and 
bolts  should  be  periodically  gone  over  and  any  loose 
one  tightened.  If  the  noise  is  due  to  the  armature 
not  being  properly  balanced,  the  makers  of  the  ma- 
chine should  be  notified,  as  this  is  due  to  faulty  con- 
struction of  the  generator. 

A  grinding  or  squeaking  noise  from  the  brushes 
can  sometimes  be  stopped  by  the  application  of  a 
very  little  vaseline  to  the  commutator.  If,  however, 
the  noise  continues,  the  brushes  should  be  removed 
and  examined  to  see  that  a  "hard  place"  has  not  de- 
veloped. Should  this  be  the  case,  the  brushes  should 
be  filed  down  past  the  "hard  place"  and  then  re- 
placed in  the  holders. 

In  the  event  of  a  short-circuit  a  fuse  would  nat- 
urally blow,  and  all  generators  should  be  fused  up 
as  near  the  terminals  as  possible. 

A  series-wound  generator  would  spark  and  pull 
the  engine  up.  It  would  not  give  any  current  to  the 
arc. 

A  compound-wound  generator  would  spark  and 
show  a  drop  in  voltage. 

A  shunt-wound  generator  would  lose  its  field  and 
would  not  excite  till  such  time  as  the  short  was  re- 
moved. 


MOTION     PICTURE     PROJECTION  379 


INSTRUCTIONS   FOR   THE   INSTALLATION 
OF  THE  "IMSCO"  1  K.  W.  MOTION  PIC- 
TURE PROJECTING  AND  32  VOLT 
INCANDESCENT  LIGHTING 
PLANT 

Carefully  remove  the  sides  and  top  of  the  crate  in 
which  the  engine  is  packed,  leaving  the  outfit  fas- 
tened to  the  wooden  skids,  which  should  not  be  re- 
moved. Transport  Engine  and  entire  equipment  to 
point  at  which  it  is  to  be  used  and  then  proceed  as 
follows : 

Prepare  Storage  Battery  for  Service 

Carefully  unpack  battery,  and  remove  the  red  soft 
rubber  nipples  and  discard  them.  Next  remove  black 
hard  rubber  vent  plugs,  which  are  standard  equip- 
ment, and  remain  on  battery  in  service. 

The  battery  cells  should  at  once  be  filled  to  bottom 
of  vent  hole  with  1.285  specific  gravity  electrolyte 
at  70°  F.  This  electrolyte  may  be  shipped  with  the 
outfit,  but  if  not,  you  will  receive  sulphuric  acid  and 
distilled  water  separately  and  you  may  proceed  to 
mix  the  electrolyte  as  follows : 

Pour  a  quantity  of  distilled  or  pure  rain  water 
into  a  clean  wooden  container.  Do  not  use  a  metal 
container  for  either  water,  acid,  or  electrolyte,  or 
the  electrolyte  will  be  of  no  use.  Next  pour  very 
carefully  into  the  water  enough  sulphuric  acid  to 
bring  the  specific  gravity  of  the  mixture  to  1.285  by 
the  hydrometer.  You  will  find  the  hydrometer  with 


380  MOTION     PICTURE     PROJECTION 

the  outfit  and  to  adjust  it  for  service,  unscrew  the 
tube  carefully,  and  remove  the  package  in  the  glass 
tube.  Remove  the  cardboard  from  the  hydrometer 
scale,  replace  it  in  the  glass  tube,  and  screw  the  rub- 
ber tube  back  in  place  again.  To  test  the  electrolyte 
simply  draw  some  of  it  into  the  glass  tube  and  hy- 


Imsco  Engine  and  Generator 

drometer  will  show  the  specific  gravity  reading.  Al- 
ways remember  that  after  testing  battery  cells  in  this 
manner  the  electrolyte  taken  out  should  be  returned 
to  the  cell  after  reading  is  taken.  Before  testing  the 
new  electrolyte,  thoroughly  stir  it  tp  make  sure  it  is 
well  mixed  and  should  you  find  that  you  have  added 
too  much  sulphuric  acid  and  the  reading  is  too  high, 
add  distilled  water  until  the  reading  is  1.285.  Never 


MOTION     PICTURE     PROJECTION  381 

pour  water  into  sulphuric  acid  (pure)  or  you  will 
likely  be  a  fit  subject  for  the  hospital.  Always  pour 
the  acid  into  the  water.  Also  never  stir  the  electro- 
lyte with  anything  but  a  clean  wooden  stick  or  mix- 
ture will  be  ruined. 

When  sulphuric  acid  is  poured  into  water  the  tem- 
perature of  the  mixture  will  be  raised  by  the  chemi- 
cal action  to  a  very  high  degree  and  it  should  be 
allowed  to  .cool  to  between  70°  and  90°  F.  before  it 
is  put  in  the  cells.  Electrolyte  above  90°  F.  will 
damage  the  cells.  Do  not  pour  electrolyte  into  the 
cells  through  a  metal  funnel  or  you  will  ruin  both 
electrolyte  and  battery.  No  metal  of  any  kind  must 
come  in  contact  with  either.  Also  under  no  circum- 
stances use  any  water  other  than  distilled  or  pure, 
clean  rain  water  caught  in  a  wooden  container.  Tap, 
well,  or  river  water  will  contain  foreign  matter  that 
will  damage  battery. 

Battery  and  Switchboard  Connections 
After  having  prepared  the  batteries  for  service, 
they  should  be  properly  connected  to  the  switch- 
board in  the  manner  shown  in  the  accompanying  dia- 
grams. Referring  to  diagram  A  (page  5)  it  will  be 
noticed  that  there  are  three  wires  from  the  battery 
to  the  three  right  hand  terminals  on  the  bottom  of 
the  switchboard.  It  is  important  that  the  connec- 
tions be  made  as  shown  and  to  prevent  confusion  the 
three  lugs  on  the  end  of  the  three  wires  supplied, 
have  different  irregular  surfaces,  making  it  impos- 
sible to  attach  any  of  them  to  the  wrong  terminal. 

The  batteries  are  shipped  in  two  units  of  eight 
cells  each  and  these  units  must  be  connected  in  series, 
as  shown  in  the  diagram,  with  the  short  wire  supplied 


382 


MOTION     PICTURE     PROJECTION 


for  this  purpose,  and  in  the  exact  manner  shown. 
That  is  to  say,  one  end  of  the  short  wire  must  be  con- 
nected to  the  white,  or  —  terminal  of  one  set  of  cells 

FRONT  VIEW  OF  SWITCH  BOARD 

SWITCH  BOARD  FOR 
IMSCO  ENeiNE, 
GENERATOR*  SETS 


B.3Z-  BZ5- 


and  the  other  end  of  the  wire  to  the  red,  or  -f-  ter- 
minal of  the  battery,  the  second  wire  to  the  white, 
or  —  terminal  of  the  twelfth  cell  of  the  battery,  and 
the  third  wire  to  the  other  white  —  terminal  at  the 
last  cell  of  the  battery.  See  that  all  connections  of 
all  the  cells  are  tight.  After  the  batteries  have  been 
filled  with  electrolyte  and  connected  as  shown  they 
are  ready  for  charging. 


MOTION    PICTURE     PROJECTION 


383 


Diagram  B  (page  5)  shows  the  complete  wiring 
diagram  and  it  will  be  seen  that  the  right  hand 
switch,  because  it  is  connected  across  only  12  cells 
of  the  battery,  delivers  current  at  25  Volts  and  this 


COMPLETE  WIRING 
DIAGRAM 


DIAGRAMMATIC 
VIEW  SHOWING 
SWITCH  BOAK.D 
TO   BATTERY 
CONNECTIONS 


SWITCH  BOAR,D  FOR, 
IMSCO  ENGrVNE 
GENERATOR,  SETS 

switch  only  should  be  used  for  the  Motion  Picture 
T29,  30  ampere  lamp.  Do  not  connect  this  lamp  to 
the  other  switch  or  it  will  immediately  burn  out.  The 
left  hand  switch,  because  it  is  connected  across  the 


384  MOTION     PICTURE     PROJECTION 

entire  battery,  or  16  cells,  will  deliver  current  at  32 
volts  and  this  switch  therefore  should  be  used  for  in- 
candescent lighting  of  the  huts  or  buildings,  or 
wherever  light  is  needed.  To  this  switch  also  may  be 
connected  any  electrical  apparatus  designed  for  32 
volts,  which  does  not  consume  a  larger  amount  of 
current  than  the  generator  is  designed  to  deliver. 
That  is  to  say,  1,000  watts.  Any  apparatus  that 
consumes  a  greater  amount  than  1,000  watts  may 
be  used  for  a  short  time  but  part  of  the  energy  will 
then  be  taken  from  the  storage  battery.  When  this 
is  done  the  battery  must  be  again  brought  up  to  its 
proper  specific  gravity  as  set  forth  under  the  head- 
ing "Charging  the  Battery." 

Diagram  C  (page  4)  shows  the  connections  on  the 
back  of  the  switchboard  and  this  should  be  studied 
so  that  you  are  familiar  with  what  takes  place  when 
the  outfit  is  in  operation.  When  the  motion  picture 
lamp  is  in  operation  the  double  throw  switch  should 
be  in  the  25  volt  position  and  the  ammeter  should 
read  30  amperes.  WTien  the  double  throw  switch  is 
in  the  25  volt  position,  it  will  be  seen  by  referring  to 
the  diagram  that  no  current  is  charged  into  the 
four  last  cells.  These  cells  will  therefore  become  dis- 
charged if  a  large  number  of  incandescent  lamps  are 
used  when  the  Double  throw  switch  is  in  the  25  volt 
position.  To  overcome  this,  when  the  outfit  is  not 
being  used  for  projection  purposes,  throw  the  switch 
into  the  32  volt  position  and  charge  the  battery  until 
all  the  cells  come  up  to  the  required  specific  gravity. 
(See  "Charging  the  battery.")  Always  have  switch 
in  32  volt  position  when  using  incandescent  lamps 
only,  or  any  32  volt  apparatus. 


MOTION    PICTURE     PROJECTION 


At  the  top  of  the  switchboard,  in  the  center,  will 
be  seen  the  automatic  cutout  which  automatically 
disconnects  the  battery  from  the  Generator  should 
the  Engine  for  any  reason  stop.  The  reason  for  this 
piece  of  apparatus  is  that,  should  the  gasoline  give 
out  or  should  any  other  circumstance  happen  that 
would  normally  stop  the  engine,  it  would  continue  to 
operate  because  the  Generator  would  operate  as  a 
motor,  taking  current  from  the  battery.  This  would 
in  a  short  time  completely  discharge  the  battery  and 
the  Automatic  cutout  is  therefore  inserted  in  the  Bat- 
tery circuit  as  a  safeguard  against  this  trouble. 

Before  starting  the  engine  observe  and  carefully 
carry  out  the  following  six  instructions: 

1.  See  that  Radiator  is  filled  with  clean  water  (it 
will  take  11  quarts)  when  the  weather  is  above  freez- 
ing (32°  F.  or  0°  C)  and  when  there  is  danger  of 
water  freezing  it  should  be  replaced  at  once  with  the 
following  solution: 

Glycerine  —  2  parts  by  volume. 
Water  —  8  parts  by  volume. 
Denatured  Alcohol  —  1  part  by  volume. 

This  solution  will  not  freeze  at  20°  below  zero  F.. 
(52°  C)  but  it  is  extremely  advisable,  when  the  tem- 
perature gets  below  0°.C.,  to  draw  off  the  water  so- 
lution, because,  should  it  freeze,  the  engine  cylinder 
or  the  water  jacket  or  both  will  crack  and  render 
outfit  absolutely  useless. 

If  for  any  reason  Glycerine  and  Alcohol  cannot 
be  obtained,  an  excellent  substitute  is  a  solution  com- 
posed  of  4.2  Ibs.  of  75  per  cent.  Calcium  Chloride  to 
each  gallon  of  water. 


386 


MOTION     PICTURE     PROJECTION 


This  solution  would  be  about  31°  beaume,  or  1.27 
specific  gravity,  which  solution  has  a  freezing  point 
of  about  55°  C.  or  23°  below  zero  F. 

Calcium  Chloride  is  much  easier  to  obtain  than 
Glycerine  and  Alcohol,  and  it  has  the  decided  ad- 
vantage in  that  it  is  much  easier  shipped. 

2.  Remove  the  handhole  plate  from  one  side  of 
crank  case  of  engine  and  pour  in  about  one  gallon  of 
the  engine  oil  that  comes  with  outfit.  When  the 
proper  amount  of  oil  is  in  the  crank  case,  the  oil 
gauge  on  the  left-hand  side  of  engine  bed  will  show 
about  two-thirds  full.  When  the  weather  is  cold, 
however,  the  oil  will  be  too  heavy  to  immediately  flow 
up  into  the  gauge  and  will  not  do  so  until  it  becomes 
warm.  If  you  place  one  gallon  in  the  crank  case  as 
above  set  forth,  you  need  have  no  apprehension.  Re- 
place plate  and  then  fill  bearing  on  Commutator  end 


Showing  Battery  Connections 


MOTION    PICTURE     PROJECTION  387 

of  Generator  with  oil  also.  This  bearing  is  a  ring 
oiled  bearing  and  once  filled  will  require  only  inter- 
mittent filling  unless  oil  is  spilled  out  when  engine  is 
shipped  around.  The  entire  engine  and  bearings, 
other  than  the  one  mentioned,  is  lubricated  by  the 
splash  system  from  the  crank  case. 

3.  See  that  Gasoline  tank  is  filled  with  gasoline 
that  has  been  strained.    Any  foreign  matter  in  gaso- 
line will'  clog  up  Carburetor  or  connections  between 
it  and  the  tank. 

4.  See  that  small  needle  valve  on  the  bottom  of 
Carburetor  is  open  one  and  one-half  turns.    The  best 
way  to  be  assured  of  this  is  to  first  close  it  tight  and 
then  open  it  the  required  amount. 

5.  See  that  small  lever  on  Breaker  Box  of  high 
tension   magneto   is   about   one-half  way   down   for 
starting  and  when  the  engine   starts   it   should  be 
pushed  down  (advanced)  as  far  as  it  will  go.     This 
lever  is  the  spark  control  lever  and  operates  exactly 
the  same  as  that  on  the  steering  post  of  an  automo- 
bile.    It  is  retarded  (up)   when  starting,   and  ad- 
vanced (down)  when  the  engine  is  running.    It  is  im- 
portant that  this  lever  be  adjusted  as  set  forth  above, 
otherwise  the  engine  will  not  operate  at  its  proper 
speed. 

6.  See  that  electrical   connections   between  mag- 
neto  and  spark  plug  and  magneto  and  switchboard 
are  tight.    Loose  connections  will  cause  a  poor  spark 
and  engine  will  not  start. 

After  the  above  adjustments  have  all  been  made 
the  engine  is  ready  to  start  and  you  should  proceed 
as  follows: 


MOTION    PICTURE     PROJECTION 


1.  Open  small  single  blade  switch  on  switchboard | 
This  switch,  when  closed,  short  circuits  the  ignition 
system  and  stops  engine.     Therefore,  the  engine  will 
not  start  until  this  switch  is  opened. 

2.  Press  finger  on  button  switch  on  circuit  breaker 
on  switchboard  for  a  few  seconds  and  the  Generator 
will  operate  as  a  motor  until  the  engine  starts.    After 
the  engine  comes  up  to  speed,  the  Generator  will  gen- 
erate current. 

Should  the  engine  not  start  after  a  few  seconds,  it 
may  be  due  to  any  of  the  following  causes : 

1.  In  very  cold  weather  gasoline,  unless  warmed, 
will  not  vaporize  and  it  is  extremely  difficult  to  start 
an  engine  under  these  conditions.     When  the  tem- 
perature is  low  and  you  experience  this  difficulty  it 
is  advisable  to  draw  off  part  of  the  water  and  heat  it. 
Hot  water  around  the  jacket  will  vaporize  the  gaso- 
line, and  engine  will  start  without  further  trouble. 

2.  Spark  plug  points  may  be  too  far  apart  or  too 
close  together.    Remove  spark  plug  with  wrench  sup- 
plied with  outfit  and  after  cleaning  points  set  them 
not  more  than  1-32"  apart,  replace  plug  tightly  in 
cylinder  head  and  connect  wire. 

3.  Cylinder  may  not  be  receiving  gasoline  from 
carburetor.     This  may  be  due  to  some  foreign  sub- 
stance clogging  the  pipe  between  the  gas  tank  and 
carburetor  or  clogging  the  small  intake  valve  con- 
trolled by  lever  at  bottom  of  carburetor.    To  remedy 
the  former,  shut  off  gasoline  at  valve  on  gas  tank, 
remove  pipe  and  see  that  it  is  clear ;  also  suck  on,  not 
blow  through  pipe  connection  on  carburetor.     The 
chances  are  very  remote  that  the  second  fault  is  pres- 
ent and  it  can  be  removed  by  holding  hand  over  air 


MOTION    PICTURE     PROJECTION  389 

intake  on  carburetor.    The  suction  from  the  cylinder 
will  clear  the  passage. 

4.  Too  Much  Gasoline.     If  the  cylinder  receives 
too  much  gasoline,  the  mixture  will  be  too  "rich"  and 
will  not  ignite.     The  gasoline  flow  is  controlled  by 
small  valve  lever  at  bottom  of  carburetor,  and  this 
should  be  open  about  one  or  one  and  a  half  full  turns. 
The  proper  amount  of  opening,  however,  will  vary 
with  temperature  and  it  is  right  when  engine  is  run- 
ning with  load  at  its  normal  speed  (about  1,250  revo- 
lutions per  minute). 

5.  Too  Little  Gasoline.     If  too  little  gas  is  being 
fed  to  cylinder  the  mixture  will  be  too  "thin"  and  will 
not  ignite.     To  determine  this,  place  hand  over  air 
intake  of  carburetor.    Do  not  interfere  with  gasoline 
intake  valve,   if  engine  continues   to   run  normally 
after  starting.     In  this  case,  all  that  was  necessary 
was  to  get  a  fairly  heavy  charge  of  gas  in-  cylinder 
for  starting.    Do  not  keep  air  intake  closed  for  more 
than  a  dozen  or  so  revolutions  of  engine  or  you  will 
flood  the  cylinder  with  pure  gasoline  and  it  will  not 
ignite. 

Seven  times  out  of  ten,  after  engine  has  once  been 
run  and  will  not  start  again,  there  is  no  gasoline  in 
tank.  A  gasoline  engine  will  not  operate  without 
gasoline.  Do  not  look  in  gasoline  tank  with  match. 

6.  Platinum  Points  in  Magneto  Breaker  Box  May 
Be  Dirty.    To  remove  cover  of  breaker  box,  slide  the 
spring  that  holds  it  over  to  one  side.     You  can  then 
lift  off  the  cover.     Clean  breaker  points  with  clean 
rag.    Do  not  scrape  them. 

When  the  engine  runs  smoothly,  take  a  piece  of 


MOTION     PICTURE     PROJECTION 


fine  sandpaper  No.  00  that  is  shipped  with  the  outfit, 
and  hold  it  on  commutator,  while  it  is  revolving,  until 
commutator  is  thoroughly  polished.  Do  not  use 
emery  or  emery  cloth.  It  will  ruin  commutator  and 
break  down  insulation.  Do  not  be  afraid  of  a  shock 
with  this  outfit.  It  cannot  generate  more  than  32 
volts  and  it  cannot  be  felt.  You  can  touch  any  part, 
any  time,  with  both  hands,  without  danger. 

It  is  necesasry  to  keep  commutator  very  clean  be- 
cause of  the  low  voltage,  and  any  grease  thereon  acts 
as  insulation  and  machine  will  not  generate  current. 
See  that  brushes  make  good  contact  with  commutator 
but  do  not  have  tension  too  tight;  just  enough  ten- 
sion on  springs  to  hold  brushes  in  place  is  all  that  is 
necesasry.  Any  greater  amount  will  cause  the 
brushes  to  wear  a  rut  in  comutator  and  impair  its 
efficiency. 

With  this  outfit  you  have  a  standard  16  cell,  32 
volt,  80  ampere  hour  Willard  Storage  Battery  and 
the  following  instructions  and  information  apply 
particularly  to  this  type  of  battery.  You  should, 
however,  be  thoroughly  familiar  with  the  practical 
operation  of  storage  batteries  in  general  and  by 
reading  carefully  the  storage  battery  data  under  the 
heading  "General  Storage  Battery  Data"  contained 
in  this  article,  you  will  then  be  in  a  far  better  posi- 
tion to  handle  this  apparatus. 

Charging  the  Battery 

As  soon  as  the  proper  connections  have  been  made 
and  the  engine  is  running  normally  and  the  batteries 
properly  filled  with  the  electrolyte  they  must  be  put 
on  charge  at  half  the  finish  rate  stamped  on  the  name 


MOTION     PICTURE     PROJECTION7 


plate.  If  this  rate  is  not  stamped  on  plate  it  is  safe 
to  assume  that  the  finish  charge  rate  is  about  five  or 
six  amperes  and  with  the  amount  of  current  showing 
on  the  ammeter  (no  lights  burning)  the  battery 
should  be  charged  continually  until  the  specific  grav- 
ity of  the  electrolyte  stops  rising.  At  this  point  all 
the  cells  should  be  "gassing"  freely  and  the  voltage 
should  read  at  least  2.4  volts  per  cell.  Test  voltage 
with  voltmeter  supplied  with  outfit.  This  voltmeter 
is  a  low  voltage  instrument  and  no  more  than  one 
cell  at  a  time  should  be  tested  with  it.  Remember 
there  are  16  cells  to  the  battery  and  you  will  get  a 
voltage  reading  from  any  one  of  them  by  placing  one 
terminal  of  the  voltmeter  on  the  positive  terminal  of 
the  other  cell  and  the  other  meter  terminal  on  the 
negative  cell  battery. 

The  amount  of  current  supplied  by  the  generator 
may  be  varied  at  will  up  to  31.25  amperes  by  increas- 
.ing  or  decreasing  the  resistance  in  series  with  the  field 
of  the  generator.  This  is  done  by  turning  the  black 
rheostat  control  wheel  on  the  switchboard.  Arrows 
on  this  wheel  show  which  way  to  turn  it  to  increase 
or  decrease  current. 

If  during  the  charge  the  temperature  of  the  elec- 
trolyte in  any  one  cell  exceeds  100°  F.  the  current 
from  the  generator  must  be  reduced  until  the  tem- 
perature falls  below  90°  F.  This  will  necessitate  a 
longer  time  to  complete  the  charge,  but  must  be 
strictly  adhered  to. 

When  the  cells  are  completely  charged  the  specific 
gravity  of  the  electrolyte  in  each  cell  should  be  be- 
tween 1.280  and  1.300.  If  above  this  (1.300)  re- 
move a  little  electrolyte  with  the  hydrometer  syringe 


392  MOTION    PICTURE     PROJECTION 

and  add  a  little  distilled  water  while  the  battery  is 
still  charging  (in  order  to  thoroughly  mix  solution) 
and  after  three  hours,  if  the  electrolyte  is  within  the 
limits  specified,  the  battery  is  ready  for  use.  If  the 
specific  gravity  of  the  electrolyte  is  below  1.280  while 
the  voltage  of  the  cells  is  about  2.4  (after  first  charge 
only)  remove  a  little  electrolyte  and  add  the  same 
quantity  of  1.400  specific  gravity  electrolyte.  Leave 
on  charge  as  before.  You  cannot  test  1.400  electro- 
lyte with  your  hydrometer,  because  the  scale  does  not 
read  that  high,  but  you  can  mix  1.400  specific  gravi- 
ty electrolyte  by  taking  seven  parts,  by  volume,  of 
pure  sulphuric  acid  and  pouring  it  into  nine  parts  of 
volume  of  distilled  water.  The  acid  should  be  poured 
into  the  water  and  allowed  to  cool  below  90°  F.  be- 
fore being  placed  in  battery  cells. 

The  standard  vent  plugs  are  now  inserted  and  the 
battery  is  ready  for  service. 

After  this  preliminary  charging  you  should  experi- 
ence no  difficulty  at  any  time  with  the  battery,  inas- 
much as  it  is,  when  properly  connected  to  the  switch- 
board, "floated"  across  the  generator  terminals  and 
when  the  generator  set  is  being  used  for  incandescent 
lighting  purposes,  that  is  to  say,  for  lighting  up  the 
huts,  etc.,  the  ammeter  should  show  about  one  am- 
pere for  every  25  watt  lamp  in  use  and  about  one 
and  one-quarter  amperes  for  each  40  watt  lamp  in 
use.  In  this  way  a  slight  amount  of  additional  cur- 
rent will  be  charged  into  the  battery  and  it  will  there- 
fore remain  continually  charged. 

Discharging  and  Recharging 

The  lights  may  be  operated  from  the  storage  bat- 
tery without  running  the  engine,  and  in  this  case 


MOTION     PICTURE     PROJECTION 


the  rate  of  discharge  will  be  according  to  the  follow- 
ing table:  i 

Delivering  hours 

1  ampere  battery  will  supply  same  for  80 

2  amperes     "  "         "         "          "    40 
4  amperes     "  "         "         "          "    20 
8  amperes     "           "         "         "         "    10 

10  amperes     «  "         "         "          "      8 

12  amperes     "  "         "         "          "      6% 

20  amperes     «  «         "         "          "      4 

30  amperes     "  "      2  2-3 

and  so  forth.  The  number  of  amperes  being  taken 
from  the  battery  may  be  found  by  multiplying  the 
number  of  lamps  in  use  by  the  wattage  of  the  lamp 
and  dividing  the  result  by  32,  which  is  the  battery 
voltage. 

For  example:    You  are  using  8  twenty-five  watt 
lamps  and  four  forty  watt  lamps. 

8x25  =  200  watts 
4x40  =  160  watts 


Total  360  watts  =  lamp  consumption  in  watts 
360 


-  =  amperes. 

32 

By  referring  to  the  preceding  table  it  will  be 
found  that  the  battery  would  discharge  12  amperes 
for  6%  hours  and  by  using  the  above  formula  you 
can  work  out  the  solution  for  any  condition. 

It  is  not  advisable  to  completely  discharge  battery 
under  any  circumstances  because  heavy  discharge 


394  MOTION    PICTURE     PROJECTION 

rates  maintained  for  any  great  length  of  time  will 
injure  the  battery. 

When  the  lights  are  operated  from  the  storage 
battery  without  the  engine  running,  the  battery 
should  be  charged  later  and  specific  gravity  read- 
ings taken  of  the  electrolyte  until  the  hydrometer 
shows  a  reading  of  from  1.280  to  1.300. 

The  large  incandescent  lamp  supplied  for  the 
motion  picture  machine  consumes  30  amperes  at  25 
volts  and  is  known  as  the  Edison  T  29  Monoplane 
Filament  Projection  Lamp.  When  using  this  lamp 
the  leads  from  the  lamp  house  must  be  connnected  to 
the  25  volt  switch  on  the  switchboard.  Under  no 
circumstances  connect  it  to  the  32  volt  switch  or 
lamp  will  immediately  burn  out.  This  lamp  may  be 
operated  for  a  short  time,  about  2  hours,  from  the 
battery,  without  the  engine  running.  This,  how- 
ever, should  only  be  done  in  case  of  emergency  and 
the  batteries  should  be  charged  as  soon  as  possible 
afterwards.  With  the  engine  running  and  the  mov- 
ing picture  30  ampere  lamp  in  operation,  the  am- 
meter on  the  switchboard  should  read  30  amperes. 
The  lamp  then  is  consuming  the  current  supplied  by 
the  generator  and  the  storage  battery  in  this  case  is 
simply  floated  across  the  line,  keeping  the  lamp  volt- 
age normal.  Do  not  try  to  operate  lamp  from  gen- 
erator without  storage  battery  connected  to  switch- 
board. 

In  cases  of  great  emergency,  where  it  is  impossi- 
ble to  take  the  engine,  the  batteries  may  be  used 
alone  to  run  the  picture  machine  and  lamps  for  a 
short  period.  Care  should  be  taken  to  connect  the 


MOTION    PICTURE     PROJECTION  395 

moving  picture  lamp  wires  to  the  twelfth  cell  ter- 
minal of  battery  and  the  lamps  used  for  lighting 
purposes  to  the  32  volt  terminal  at  the  sixteenth  or 
last  cell. 

As  before  stated,  the  battery  alone,  under  no  cir- 
cumstances, should  be  used  in  connection  with  the 
motion  picture  lamp  for  a  longer  period  than  2 
hours  because  the  battery  will  become  overdis- 
charged.  The  amount  of  current  still  in  battery 
can  be  determined  by  testing  the  electrolyte  with 
the  hydrometer  and  it  should  not  be  allowed  to  drop 
below  1175,  after  which  it  should  be  charged  from 
the  generator  at  from  10  to  15  amperes  until  the 
specific  gravity  of  the  electrolyte  reaches  about 
1265  and  then  the  amperes  should  be  reduced  to 
about  5  and  the  charge  continued  until  the  electro- 
lyte reading  is  between  1275  and  1300. 

Regulating  Engine  to  Procure  Proper  Amperage. 
The  amount  of  current  delivered  by  the  generator  is 
in  direct  proportion  to  the  amount  flowing  through 
the  shunt  field  of  the  machine.  It  may  be  varied  up 
to  31^4  amperes  by  adjusting  the  rheostat  control 
wheel  on  the  front  of  the  switchboard.  The  genera- 
tor will  not  deliver  its  full  capacity  unless  the  en- 
gine is  running  at  its  normal  speed  of  1250  revolu- 
tions per  minute.  Should  the  engine  be  running  too 
slow  with  generator  delivering  current  the  carburetor 
on  the  engine  may  be  delivering  too  much  or  too 
little  gasoline  and  this,  as  previously  stated,  may  be 
adjusted  by  means  of  the  small  needle  valve  lever  on 
the  bottom  of  the  carburetor. 


396  MOTION     PICTURE     PROJECTION 

Care  of  the  Battery 

In  the  proper  care  of  a  storage  battery  if  the  fol- 
lowing things  are  remembered  you  will  escape  75 
per  cent  of  your  battery  troubles : 

First — Test  the  specific  gravity  of  all  cells  with  a 
hydrometer  two  or  three  times  a  month.  If  any  of 
the  cells  are  below  1200,  the  battery  is  more  than 
half  discharged,  and  it  should  be  charged  with  the 
ammeter  on  the  switchboard  reading  10  amperes, 
until  the  normal  specific  gravity  is  reached  (1275 
to  1300). 

Second — Pure  water  must  be  added  to  all  cells 
regularly  and  at  sufficiently  frequent  intervals  to 
keep  the  solution  at  the  proper  height.  Add  water 
until  solution  is  one-half  inch  above  top  of  plates. 

Never  let  solution  get  below  top  of  plates. 

Plugs  must  be  removed  to  add  water,  then  re- 
placed and  screwed  on  after  filling. 

The  battery  should  be  inspected  and  filled  with 
water  once  every  week  in  warm  weather  and  once 
every  two  weeks  in  cold  weather. 

Do  not  use  Acid  or  Electrolyte,  only  pure  water. 

Do  not  use  any  water  known  to  contain  even  small 
quantities  of  salts  or  iron  of  any  kind. 

Distilled  water  or  fresh,  clean  rain  water  only 
should  be  used. 

Use  only  a  clean  vessel  for  handling  or  storing 
water. 

Add  water  regularly,  although  the  battery  may 
seem  to  work  all  right  without  it. 

In  order  to  avoid  freezing  of  the  battery,  it  should 
always  be  kept  in  a  fully  charged  condition.  A  fully 


MOTION     PICTURE     PROJECTION  397 

charged  battery  will  not  freeze  in  temperatures  or- 
dinarily met. 

Electrolyte  will  freeze  as  follows: 

Sp.  gr.  1,150,  battery  empty,  20  above  zero  F. 
Sp.  gr.  1,180,  battery  %  discharged,  zero  F. 
Sp.  gr.  1,215,  battery  %  discharged,  20  below  zeroF. 
Sp.  gr.  1,250,  battery  %  discharged,  60  below  zero  F. 

Therefore,  it  will  be  seen  that  there  is  no  danger 
of  the  battery  freezing  up  if  it  kept  at  a  specific 
gravity  of  from  1250  to  1300  and  it  should  be  kept 
as  near  1275  as  possible.  Under  no  circumstances 
should  acid  or  electrolyte  be  added  to  the  cells  to 
bring  them  up  to  the  required  specific  gravity. 
Nothing  but  pure  water  must  be  put  in  the  cells 
after  the  battery  has  been  once  placed  in  commission 
and  the  specific  gravity  must  be  kept  up  by  charg- 
ing only. 

General  Storage  Battery  Data 

A  storage  battery,  secondary  battery,  or  accumu- 
lator, as  it  is  variously  called,  is  an  electrical  device 
in  which  chemical  action  is  first  caused  by  the  pas- 
sage of  electric  current,  after  which  the  device  is 
capable  of  giving  off  electric  current  by  means  of 
secondary  reversed  chemical  action.  Any  voltaic 
couple  that  is  reversible  in  its  action  is  a  storage 
battery.  The  process  of  storing  electric  energy  by 
the  passage  of  current  from  an  external  source,  is 
called  charging  the  battery;  when  the  battery  is 
giving  off  current,  it  is  said  to  be  discharging.  A 
storage  battery  cell  has  two  elements  or  plates,  and 
an  electrolyte.  The  two  plates  are  usually  made 
of  the  same  material,  though  they  may  be  of  two 


398  MOTION     PICTURE     PROJECTION 

different  materials.  The  material  used  in  the  con- 
struction of  both  plates  of  battery  furnished  is  lead. 

Polarity. — The  terms  positive  and  negative  are 
employed  to  designate  the  direction  of  the  flow  of 
current  to  or  from  the  battery ;  that  is,  the  positive 
plate  is  the  one  from  which  the  current  flows  on  dis- 
charge, and  the  negative  plate  is  the  one  into  which 
current  flows  on  discharge.  In  a  lead  battery  the 
positive  plate,  on  which  the  lead  peroxide  is  formed, 
has  a  comparatively  hard  surface  of  a  reddish- 
brown  or  chocolate  color,  while  the  negative  plate, 
which  carries  the  sponge  lead,  has  a  much  softer 
surface  of  a  grayish  color. 

Electrolyte. — The  electrolyte  used  with  the  lead 
type  of  battery  is  always  a  diluted  solution  of  sul- 
phuric acid.  The  specific  gravity  of  the  electrolyte 
when  the  battery  is  fully  charged,  varies  from  about 
1.210  for  stationary  batteries  to  1.300  for  auto- 
mobile ignition  batteries  and  other  portable  bat- 
teries. 

The  proper  specific  gravity  to  use  varies  with  the 
conditions,  and  the  specific  gravity  may  be  found 
by  the  use  of  a  hydrometer.  When  the  cells  of  the 
battery  shipped  with  this  outfit  are  fully  charged, 
the  specific  gravity  of  the  electrolyte,  as  indicated 
by  the  hydrometer,  should  be  1275  to  1300  at  70 
degrees  F.  The  final  density  is  the  usual  practice. 
None  but  sulphur  or  brimstone  acid  should  be  used. 
When  diluting,  the  acid  must  be  poured  into  the 
water  slowly  and  with  great  caution. 

Never  Pour  the  Water  into  the  Acid. — The 
specific  gravity  of  commercial  sulphuric  acid  is 
1.835,  and  1  part  of  such  acid  should  be  mixed 


MOTION    PICTURE     PROJECTION 399 

with  5  parts  (by  volume)  of  pure  water.  Care 
should  be  taken  that  no  impurities  enter  the  mix- 
ture. The  vessel  used  for  the  mixing  must  be  a 
lead-lined  tank  or  one  of  wood  that  has  never  con- 
tained any  other  acid;  a  wooden  washtub  or  spirits 
barrel  answers  very  well.  The  electrolyte  when  plac- 
ed in  the  cell  should  come  %  inch  above  the  top  of 
the  plates.  Before  putting  the  electrolyte  in  the 
cells,  the  positive  pole  of  each  cell  should  be  con- 
nected to  the  negative  pole  of  the  next  cell  in  the 
series  and  the  whole  battery  of  cells  should  be  con- 
nected, through  a  main  switch,  to  the  charging 
source — the  positive  pole  of  the  baattery  to  the  posi- 
tive side  of  the  charging  source,  and  the  negative 
pole  to  the  negative  side.  After  adding  the  electro- 
lyte the  battery  should  be  charged  at  once  or  at 
least  inside  of  2  hours.  A  little  pure  water  should 
be  added  occasionally  to  the  electrolyte  to  make 
up  for  evaporation,  and  a  small  quantity  of  acid 
should  be  added  about  once  a  year  to  make  up  for 
that  thrown  off  in  the  form  of  spray  or  that  ab- 
sorbed by  the  sediment  in  the  cells.  Do  not  use 
anything  but  pure  distilled  water  in  storage  bat- 
teries because  any  impurities  such  as  those  com- 
monly found  in  tap  or  well  water  will  in  a  very 
short  time  absolutely  ruin  the  battery. 

Test  of  Specific  Gravity — The  specific  gravity 
of  the  electrolyte  is  the  most  accurate  guide  as  to 
the  state  of  charge  of  a  lead-type  storage  battery. 
The  test  of  the  specific  gravity  is  made  by  means 
of  a  hydrometer  having  a  suitable  scale  for  the  type 
of  cell  to  be  tested.  In  all  portable  types  of  bat- 
teries, and  ordinarily  in  vehicle  batteries,  it  is  usu- 
ally necessary  to  draw  some  of  the  electrolyte  from 


400  MOTION    PICTURE    PROJECTION 

the  cell  in  order  to  test  its  specific  gravity  with  the 
hydrometer,  which  should  have  a  scale  reading  from 
1150  to  1300. 

Charging — The  normal  charging  rate  is  the  same 
as  the  8  hour  discharge  rate  specified  by  manufac- 
turers. The  charge  should  be  continued  uninter- 
ruptedly until  complete ;  but  if  repeatedly  carried 
beyond  the  full-charge  point,  unneccessary  waste 
of  energy,  a  waste  of  acid  through  spraying,  a 
rapid  accumulation  of  sediment,  and  a  shortened 
life  of  the  plates  will  result.  At  the  end  of  the  first 
charge,  it  is  advisable  to  discharge  the  battery  about 
one-half,  and  then  imemdiately  recharge  it.  It  is 
advisable  to  overcharge  the  batteries  slightly  about 
once  a  week,  in  order  that  the  prolonged  gassing 
may  thoroughly  stir  up  the  electrolyte  and  also  to 
correct  inequalities  in  the  voltages  of  the  cells.  If 
the  discharge  rate  is  very  low,  or  if  the  battery  is 
seldom  used,  it  should  be  given  a  freshening  charge 
weekly. 

Indications  of  a  Complete  Charge — A  complete 
charge  should  be  from  12  to  15%  greater  in  am- 
pere-hours than  the  preceding  discharge.  The  prin- 
ciple indications  of  a  complete  charge  are:  (1)  The 
voltage  reaches  a  maximum  value  of  2.4  to  2.7  per 
cell,  and  the  specific  gravity  of  the  electrolyte  a 
maximum  of  1275  to  1300  per  cell.  If  all  the  cells 
are  in  good  condition  and  the  charging  current  is 
constant,  maximum  voltage  and  specific  gravity  are 
reached  when  there  is  no  further  increase  for^4  to  % 
hour.  (2)  The  amount  of  gas  given  off  at  the  plates 
increases  and  the  electrolyte  assumes  a  milky  ap- 
pearance, or  is  said  to  boil. 


MOTION     PICTURE     PROJECTION  401 

Voltage  Required — The  voltage  at  the  end  of  a 
charge  depends  on  the  age  of  the  plates,  the  temper- 
ature of  the  electrolyte,  and  the  rate  of  charging;  at 
normal  rate  of  charge  and  at  normal  temperature, 
the  voltage  at  the  end  of  the  charge  of  a  newly  in- 
stalled battery  will  be  2.5  volts  per  cell  or  higher; 
as  the  age  of  the  battery  increases,  the  point  at  which 
it  will  be  fully  charged  is  gradually  lowered  and  may 
drop  as  low  as  2.4  volts.  All  voltage  readings  are 
taken  with  the  current  flowing;  readings  taken  with 
the  battery  on  open  circuit  are  of  little  value  and 
are  frequently  misleading.  After  the  completion  of 
a  charge  and  when  the  current  is  off,  the  voltage  per 
cell  will  drop  rapidly  to  2.05  volts  and  remain  there 
for  some  time  while  the  battery  is  on  open  circuit. 
When  the  discharge  is  started,  there  will  be  a  fur- 
ther drop  to  2  volts,  or  silghtly  less,  after  which  the 
decrease  will  be  slow.  Cells  should  never  be  charged 
at  the  maximum  rate  except  in  cases  of  emergency. 

Direction  of  Current — The  charging  current  must 
always  flow  through  the  battery  from  the  positive 
pole  to  the  negative  pole.  If  it  is  necessary  to  test 
the  polarity  of  the  line  wires  when  no  instruments 
are  available,  attach  two  wires  to  the  mains,  connect 
some  resistance  in  series  to  limit  the  current,  and  dip 
the  free  ends  of  the  wires  into  a  glass  of  acidulated 
water,  keeping  the  ends  about  1  inch  apart.  Bub- 
bles are  given  off  most  freely  from  the  negative  end. 

Discharging — Heavy  overdischarge  rates  main- 
tained for  a  considerable  time,  are  almost  sure  to 
injure  the  cells.  The  normal  discharge  rate  should 
not  be  exceeded  except  in  case  of  emergency.  The 
amount  of  charge  remaining  available  at  any  time 


402  MOTION     PICTURE     PROJECTION 

can  be  determined  from  voltage  and  specific-gravity 
readings.  During  the  greater  part  of  a  complete 
discharge,  the  drop  in  voltage  is  slight  and  very 
gradual;  but  near  the  end  the  falling  off  becomes 
much  more  marked.  Under  no  circumstances  should 
a  battery  ever  be  discharged  below  1.7  volts  per 
cell,  and  in  ordinary  service  it  is  advisable  to  stop 
the  discharge  at  1.75  or  1.8  volts.  If  a  reserve  is 
to  be  kept  in  the  battery  for  use  in  case  of  emer- 
gency, the  discharge  must  be  stopped  at  a  corre- 
spondingly higher  voltage.  The  fall  in  density  of 
the  electrolyte  is  in  direct  proportion  to  the  ampere- 
hours  taken  out,  and  is  therefore  a  reliable  guide  as 
to  the  amount  of  discharge. 

Miscellaneous  Points 

Restoring  Weakened  Cells  —  There  are  several 
methods  of  restoring  cells  that  have  become  low:  (1) 
Overcharge  the  whole  battery  until  the  low  cells  are 
brought  up  to  the  proper  point,  being  careful  not 
to  damage  other  cells  in  the  battery.  (2)  Cut  the 
low  cells  out  of  circuit  during  one  or  two  discharges 
and  in  again  during  charge.  (3)  Give  the  defective 
cells  an  individual  charge.  Before  putting  a  cell 
that  has  been  defective  into  service  again,  care  should 
be  taken  to  see  that  all  the  signs  of  a  full  charge  are 
present. 

Sediment  in  Cells — During  service,  small  parti- 
cles drop  from  the  plates  and  accumulate  on  the  bot- 
tom of  the  cells.  This  sediment  should  be  carefully 
watched,  especially  under  the  middle  plates  where  it 
accumulates  most  rapidly,  and  should  never  be  al- 
lowed to  touch  the  bottom  of  the  plates  and  thus 


MOTION     PICTURE     PROJECTION  403 

short-circuit  them.  If  there  is  any  free  space  at 
the  end  of  the  cells,  the  sediment  can  be  raked  from 
under  the  plates  and  then  scooped  up  with  a  wooden 
ladle  or  other  non-metallic  device.  If  this  method 
is  impracticable,  the  electrolyte,  after  the  battery 
has  been  fully  charged,  should  be  drawn  off  into 
clean  containing  vessels ;  the  cells  should  then  thor- 
oughly washed  with  water  until  all  the  sediment  is 
removed,  and  the  electrolyte  should  be  replaced  at 
once  before  the  plates  have  had  a  chance  to  become 
dry.  In  addition  to  the  electrolyte  withdrawn,  new 
electrolyte  must  be  added  to  fill  the  space  left  by  the 
removal  of  the  sediment ;  the  new  electrolyte  should 
be  of  1.3  or  1.4  sp.  gr.  in  order  to  counteract  the 
effect  of  the  water  absorbed  by  the  plates  while  be- 
ing washed.  If  at  any  time  any  impurities,  espe- 
cially any  metal  other  than  lead  or  any  acid  other 
than  sulphuric  acid,  gets  into  a  cell,  the  electrolyte 
should  be  emptied  at  once  and  the  cells  thoroughly 
washed  and  filled  with  pure  electrolyte. 

Idle  Batteries. — If  a  battery  is  to  be  idle  for,  say. 
6  months  or  more,  it  is  usually  best  to  withdraw  the 
electrolyte,  as  follows:  After  giving  a  complete 
charge,  siphon  or  pump  the  electrolyte  into  con- 
venient receptacles,  preferably  carboys  that  have 
previously  been  cleaned  and  have  never  been  used  for 
any  other  kind  of  acid.  As  each  cell  is  emptied,  im- 
mediately refill  it  with  water;  when  all  the  cells  are 
filled,  begin  discharging  and  continue  until  the  volt- 
age falls  to  or  below  1  volt  per  cell  at  normal  load, 
and  then  draw  off  the  water. 


404  MOTION     PICTURE     PROJECTION 

Putting  Battery  into  Commission* — To  put  an 
idle  battery  into  commission,  first  make  sure  that  the 
connections  are  right  for  charging;  then  remove  the 
water,  put  in  the  electrolyte,  and  begin  charging  at 
once  at  the  normal  rate.  From  25  to  30  hour  con- 
tinuous charging  will  be  required  to  give  a  complete 
charge. 

Svlphating — Lead  sulphate  is  practically  an  in- 
sulator. Some  of  this  material  is  formed  in  all  lead- 
sulphuric-acid  storage  cells  on  discharge  and  is  re- 
converted to  lead  oxide  or  lead  peroxide  on  recharg- 
ing the  cell.  If  present  in  excessive  quantities,  the 
sulphate  adheres  to  the  plates,  especially  the  posi- 
tive, in  white  soluble  patches,  preventing  chemical 
action,  increasing  the  resistance  of  the  cell,  and 
causing  unequal  mechanical  stresses  that  may  buckle 
the  plates.  The  most  frequent  causes  of  sulphating 
are  overdis charging,  too  high  specific  gravity  of 
electrolyte,  and  allowing  the  battery  to  stand  for  a 
considerable  length  of  time  in  a  discharged  condi- 
tion. 


*This  does  not  apply  to  battery  received  with  this 
outfit  because  it  has  been  fully  charged  before  leav- 
ing the  factory  and  still  holds  this  charge  because 
the  electrolyte  was  drawn  off  after  a  complete  charge 
and  the  cells  hermetically  sealed  with  the  red  rubber 
caps.  After  you  commence  charging  as  set  forth  in 
a  previous  paragraph  it  will  take  only  a  fraction  of 
the  time  set  forth  in  the  above  paragraph  to  bring 
the  battery  up  to  its  full  capacity. 


MOTION"     PICTURE     PROJECTION  405 

Theory  of  the  Engine 

In  order  to  be  able  to  understand  the  machine,  it 
will  be  necessary  for  you  to  have  a  rudimentary 
knowledge  of  what  goes  on  inside  the  engine. 

To  begin:  In  order  to  have  power  we  must  use 
some  heat  agent — in  this  instance  gasoline.  Our 
1  K.  W.  plant  as  usually  operated  consumes  one 
pint  of  gasoline  per  hour  and  burns  about  460  cubic 
feet  of  air  mixed  with  the  gasoline.  The  mixing  of 
gasoline  and  air  is  done  in  the  carburetor  and  we  will 


Switchboard  Showing  Automatic  Cut-Out,  Starting  Switch, 
Voltmeter,  Ammeter,  Field  Regulator,  25  and  32- Volt  Switches 

hereafter  call  the  mixture  of  air  and  gasoline,  Gas. 
This  gas  is  explosive  and  can  be  ignited  by  an  elec- 
tric spark  and  with  compression  and  proper  igni- 
tion, will  give  power  and  turn  the  shaft  as  follows : 


406 


MOTION     PICTURE     PROJECTION 


Referring  to  (Fig.  1,  Plate  H),  we  see  the  gas 
coming  from  the  carburetor  (G)  through  the  valve 
(I),  called  the  inlet  valve,  into  the  cylinder.  The 
piston  (P)  is  moving  downward  as  shown  by  the 
arrow,  it  being  at  this  time  pulled  downward  by  the 
connecting  rod  (R)  which  is  pulled  downward  by  the 
crank  (A)  on  the  shaft  (S)  which  is  (we  will  say) 
being  revolved  by  the  generator  at  first.  The  move- 


Side  View  Showing  Bosch  Magneto 

ment  of  the  piston  downward  creates  a  partial 
vacuum  and  at  the  same  time  the  inlet  valve  opens 
and  gas  rushes  through  the  carburetor  and  through 
the  intake  pipe  (H)  and  from  there  past  the  valve 
(I)  into  the  cylinder  to  fill  this  partial  vacuum. 
The  intake  valve  opens  at  the  beginning  of  the 
stroke,  or  nearly  that,  according  to  the  ideas  of  the 
designing  engineer.  At  the  bottom  of  the  stroke  the 
intake  valve  will  close,  and  we  then  have  a  volume  of 


MOTION     PICTURE     PROJECTION  407 

gas,  retained  in  the  combustion  chamber  and  space 
in  the  cylinder,  through  which  the  piston  has  passed. 

As  the  crank  continues  to  revolve  (we  refer  to  Fig. 
2,  in  which  you  see  both  valves  closed),  the  advanc- 
ing piston  is  decreasing  the  size  of  the  space  contain- 
ing the  gas,  hence  putting  same  under  compression, 
which  in  this  engine  ranges  between  40  and  50  pounds 
per  square  inch.  At  the  moment  the  piston  arrives 
at  the  top  of  the  stroke,  or  dead  center  (being  when 
the  crank  A)  and  the  connecting  rod  (R)  are  in 
line),  the  charge  of  gasoline  vapor  and  air  is  ex- 
ploded by  means  of  an  electric  spark,  generally  given 
with  a  spark  plug  (U)  described  later.  Upon  firing, 
the  expansion  of  the  gas  is  very  great,  causing  a 
pressure  of  200  to  300  pounds  to  the  square  inch  and 
thus  forcing  the  piston  downward  again,  as  shown  in 
Fig.  3,  which  is  called  the  power  stroke,  or  the  ex- 
.  plosion  stroke. 

We  now  have  had  the  intake  stroke,  the  compres- 
sion stroke,  and  the  power  stroke.  After  the  power 
stroke  has  arrived  at  the  limit  of  downward  move- 
ment, we  may  get  rid  of  the  burned  gases  in  order  to 
be  ready  for  a  fresh  charge,  and  that  is  accomplished 
by  the  mechanical  opening  of  the  exhaust  valve  (E) 
the  moment  the  piston  is  about  to  start  upward,  and 
the  piston  then  pushes  the  gas  out  through  this  valve 
and  through  the  pipe  (M)  into  the  muffler,  or  into 
the  air  if  there  is  no  muffler. 

We  have  described  the  four  cycles,  each  cycle  be- 
ing represented  as  we  have  seen,  by  intake,  compres- 
sion, power  and  exhaust  strokes  respectively. 


408  MOTION     PICTURE     PROJECTION 


The  Spark  Plug 

A  spark  plug  is  a  device  so  constructed  as  to  make 
an  electrical  gap  across  which  the  electric  spark 
jumps  and  is  to  be  exposed  to  the  gases  in  the  cylin- 
der, firing  them  as  a  consequence. 

There  are  many  kinds  of  spark  plugs,  the  most 
universal  probably  being  the  same  as  used  on  this 
engine,  there  being  an  electrode,  or  wire,  running 
down  through  the  center  of  a  porcelain  core,  this 
being  surrounded  by  metal  threaded  parts  which 
screw  into  the  cylinder,  and  from  which  the  central 
electrode  is  insulated  by  the  porcelain.  The  end  of 
the  central  electrode  is  brought  to  within  a  short 
distance  of  the  extension  of  the  outer  metal  shell  on 
the  exposed  part  of  the  spark  plug  inside  the  cylin- 
der. One  wire  from  the  magneto  is  connected  to  this. 


MOTION     PICTURE     PROJECTION  409 

central  electrode  on  top  of  the  spark  plug  by  means 
of  the  thumb  nut  thereon.  The  ground  is  through 
the  base  of  the  magneto  to  the  engine,  thereby  com- 
pleting the  circuit,  when  the  spark  plug  jumps  across 
the  gap  between  the  point  of  the  electrode  and  the 
extension  of  the  metal  case  of  the  spark  plug. 

For  magneto  service  these  extremities  should  be 
adjusted  to  about  1-50  inch  gap.  If  they  are  too 
wide  apart  there  will  be  trouble  in  missing. 

Be  sure  all  wire  connections  are  tight. 

Magneto  and  Spark  Plug  Test 

If  at  any  time  you  wish  to  determine  whether  the 
magneto  is  firing  properly,  simply  disconnect  the 
wire  at  the  spark  plug,  and  holding  the  wire  1-8  inch 
from  engine  at  any  point,  and  see  if  the  spark  jumps 
across  the  engine  in  motoring  or  running. 

To  try  the  spark  plug  for  firing,  remove  the  plug 
.from  the  cylinder  head  with  special  wrench  provided, 
then  reattach  wire  to  the  plug  and  lay  the  plug  on 
the  engine. 

Compression  Test 

Try  compression  by  turning  the  flywheel  over  to 
bring  the  piston  up  on  the  compression  stroke.  If 
this  turns  over  without  resistance,  your  engine  has 
for  some  reason  'lost  its  compression."  As  there  are 
only  four  openings  into  your  compression  chamber 
you  can  quickly  try  these  out  individually.  First, 
the  spark  plug  hole.  A  little  oil  poured  around  the 
plug  will  show  bubbles  when  you  bring  the  piston  up 
for  compression  if  there  is  any  leakage  at  this  point. 
Most  probably  the  leaking  is  through  either  the  in- 
take or  exhaust  valves.  Unscrew  the  nuts  on  top  of 


410 


MOTION     PICTURE     PROJECTION 


cylinder  head  and  take  off  complete  cylinder  head 
and  valves  for  examination.  On  both  of  these  valves 
you  will  find  slots  on  top  in  which  you  can  use  a 
screwdriver  for  turning  the  valves  back  and  forth 
to  work  any  deposit  or  carbon  or  foreign  matter 
that  may  be  preventing  them  from  making  a  tight 
seat.  If  dirty,  clean  thoroughly  with  gasoline.  With 
these  tight,  and  still  no  compression,  it  must  be  a 
leakage  past  the  piston.  This  is  practically  impos- 
sible in  this  engine,  unless  you  have  run  it  "dry"  and 
stuck  or  broken  the  piston  rings. 

In  General 

In  general,  the  best  advice  is  to  leave  all  parts  of 
the  engine  alone  until  you  have  carefully  thought  out 
where  the  trouble  probably  lies  and  what  is  causing 
it,  and  this  can  be  clearly  and  accurately  done  by  the 
most  inexperienced  man  if  he  will  only  bear  in  mind 


L 


COUPLING 


GENERATOR. 
FIG.  1 


MOTION     PICTURE     PROJECTION  411 

and  trace  out  the  three  lines,  compression,  ignition 
and  mixture. 

The  generator  is  shunt  wound  which  is  the  sim- 
plest form  of  generator  used.  Fig.  1  gives  cross  sec- 
tion of  same.  "A"  Ts  armature  which  revolves  in 
fields  "F"  and  shaft  of  armature  being  fastened  to 
engine  shaft  as  shown  by  coupling  is  turned  at  en- 
gine speed.  The  field  windings  "W"  energizes  the 
fields  and  consist  of  many  turns  of  fine  wire.  The 
armature  windings  as  they  pass  through  the  lines  of 
force  produced  by  fields  generate  electrical  power 
which  is  collected  from  the  commutator  "C"  and  de- 
livered to  the  battery  and  service  lines  as  required. 

There  is  only  one  bearing  on  generator  which  is  as 
shown,  the  split  coupling  connecting  armature  shaft 
to  engine  shaft  constituting  the  other  bearings. 


FIG.  2 


By  referring  to  Fig.  No.  2  the  wiring  diagram  will 
be  seen  for  a  shunt  wound  generator.  Fig.  No.  3 
shows  the  same  as  it  is  actually  arranged  on  the  gen- 
erator. The  fields  "H"  are  wound  around  the  pole 
pieces  and  the  two  wires  leading  to  them  join  the 
armature  leads  (A)  and  (B)  at  (M)  and  (N)  or  as 
the  name  implies  the  shunt  wound  generator  means 


412 


MOTION     PICTURE     PROJECTION 


MOTION     PICTURE     PROJECTION  413 

that  the  field  windings  are  shunted  or  paralleled  with 
the  armature  leads. 

Fig.  4  shows  the  armature  and  fields  and  as  noted 
the  field  poles  alternate  North  pole  and  South  pole 
magnetism.  This  could  be  compared  to  -(-  and  ( — ), 
the  North  pole  comparing  to  +  and  South  pole  to 
( — ),  because  the  lines  of  force  flow  from  (N)  to  (S) 
as  current  always  flows  from  +  to  ( — ). 

Referring  again  to  Fig.  4  the  lines  of  force  pro- 
duced by  the  fields  flow  from  the  (N)  poles  through 
the  iron  body  of  the  armature  to  the  South  poles  and 
return  to  the  (N)  poles  through  the  outside  frame 
of  the  generator. 

As  the  windings  of  armature  as  represented  pass 
through  the  lines  of  force,  electric  current  is  gen- 
erated which  is  collected  and  delivered  by  the  com- 
mutator to  the  service  lines  or  battery. 


414  MOTION     PICTURE     PROJECTION 

ELECTRICAL  APPARATUS  FOR  THE 
STUDIO  AND   THEATRE 

The  question  of  whether  alternating  or  direct  cur- 
rent should  be  used  in  the  production  or  projection 
of  motion  pictures  is  no  longer  open  for  argument. 

Studio  engineers  and  projectionists  are  quite 
familiar  with  the  decided  advantages  of  direct  cur- 
rent from  the  standpoint  of  both  economy  and  good 
illumination.  In  fact,  a  comparison  of  the  cost  of 
operation  per  candle  power  and  the  relative  photo- 
graphic value  is  so  much  in  favor  of  direct  current 
that  it  is  almost  universally  employed.  To-day,  al- 
ternating current  for  motion-picture  work  can  be 
considered  a  deviation  from  standard  practice. 

A  motor  generator  is  conceded  to  be  the  most  sat- 
isfactory piece  of  apparatus  to  convert  A.  C.  to  D. 
C.  for  use  either  in  the  studio  or  theatre.  Before 
proceeding,  however,  into  the  discussion  of  generat- 
ing and  converting  equipment,  let  us  consider  briefly 
the  respective  requirements  for  satisfactory  illumina- 
tion in  the  studio  and  theatre,  then  we  shall  discuss 
in  a  general  way  the  design  of  apparatus  suitable  to 
meet  these  requirements. 

For  best  results  in  studio  lighting,  the  Mercury 
Vapor  tubes  for  producing  the  soft  lights  as  well  as 
the  arcs  used  for  contrast  and  "close-ups,"  must  be 
supplied  with  a  very  steady  direct  current.  The 
motion-picture  camera  is  very  susceptible  to  fluctua- 
tions in  light  resulting  from  unsteady  voltage ;  there- 
fore, generating  or  converting  apparatus,  suitable  for 
stage  lighting,  must  have  electrical  characteristics 
to  conform  with  this  essential  requirement. 


MOTION     PICTURE     PROJECTION 


415 


Economical  distribution  is  of  unusual  importance 
in  the  studio  on  account  of  the  large  number  of  cir- 
cuits and  heavy  current  handled.  The  three-wire 
system  is  used  considerably  because  of  the  saving  in 
copper  in  making  the  installation. 

In  connection  with  the  three-wire  system  of  dis- 
tribution, a  very  important  item  is  the  matter  of 
flexibility.  The  studio  director  is  very  liable  to  call 
for  "lights"  or  a  change  in  the  illumination,  which 
would  result  in  an  unbalanced  circuit  greatly  in  ex- 
cess of  that  for  which  commercial  three-wire  genera- 
tors or  converters  are  designed.  Even  if  it  were  pos- 
sible for  the  electrician  to  connect  the  circuits  so  as 
to  obtain  a  balanced  condition,  the  time  required  to 
make  the  proper  connections  would  prove  a  detriment 


Westinghouse  Motor  Generator  for  Motion  Picture  Projection 


416 


MOTION     PICTURE     PROJECTION 


Three  Unit  Motor  Generator  for  Studio  Lighting,  Consisting 

of  Two  150  Kil.   Generators   and  50  Cycle  Induction 

Motor.     Part  Installation  in  Robert  Brunton 

Studios,  Los  Angeles,  Cal. 


MOTION     PICTURE     PROJECTION  417 

to  rapid  production.  Every  minute  counts — time  is 
very  valuable  in  the  present-day  production  of  mo- 
tion pictures.  Also  the  matter  of  convenience  should 
be  given  consideration.  Assuming  that  the  load  could 
be  kept  balanced,  or  nearly  so,  by  making  the  proper 
connections,  this  work  of  plugging  in  the  different 
circuits  so  as  to  obtain  a  nearly  balanced  load  would 
prove  very  inconvenient.  For  these  reasons  this  fre- 
quent condition  of  large  unbalanced  loads  introduces 
a  great  objection  to  the  application  of  commercial 
three-wire  apparatus  designed  to  carry  not  over  25 
per  cent,  unbalanced  current. 

Westinghouse  three-unit  motor  generators  meet  all 
the  requirements  indicated  above.  They  consist  of 
two  115  volts,  flat  compound,  direct-current  genera- 
tors, mounted  on  a  common  base  with  and  directly 
connected  to  a  synchronous  or  induction  motor  of 
the  proper  characteristics.  The  generators  are  con- 
nected in  series  and  a  lead  brought  out  from  the  in- 
termediate point  forms  the  neutral  for  the  three-wire 
system.  Each  machine  will  carry  its  full  rated  load 
independent  of  the  other ;  therefore  the  motor  genera- 
tor will  operate  satisfactorily  under  a  50  per  cent, 
unbalanced  kilowatt  or  100  per  cent,  unbalanced  am- 
pere load.  These  generators  give  a  constant  voltage 
characteristic,  because  they  are  designed  for  flat 
voltage  regulation  over  a  wide  range  of  load,  and 
their  use  provides  for  a  most  flexible  three-wire  dis- 
tribution system.  The  Westinghouse  Company  is  a 
pioneer  in  recommending  and  furnishing  this  type  of 
apparatus  for  stage  lighting.  Studio  engineers  were 
quick  to  recognize  its  relative  merits,  consequently 


418  MOTION     PICTURE     PROJECTION 


Westinghouse   Generator   Showing   Rheostats   and   Control 


MOTION     PICTURE     PROJECTION  419 

the  position  of  the  three-unit  motor  generator  is  fully 
established. 

The  one  most  essential  requirement  for  best  results 
in  motion-picture  projection  is  direct  current  of  con- 
stant value  at  all  times.  The  importance  of  this  re- 
quirement is  fully  appreciated  when  one  considers 
that  any  fluctuations  of  current  in  the  arc  circuit 
causes  a  corresponding  irregularity  in  the  candle 
power  developed,  which  is  noticeable  on  the  screen. 
It  should  be  borne  in  mind  that  the  public  is  paying 
mainly  for  results  produced  on  the  screen,  and  any 
unsteady  light,  which  detracts  from  the  picture,  is 
always  accompanied  by  a  tremendous  hazard  of  los- 
ing patronage. 

Westinghouse  motion-picture  equipment  fulfills 
this  essential  requirement  for  successful  projection 
of  the  picture  in  the  theatre^  This  equipment  con- 
sists of  chiefly  a  two-unit  motor  generator  with  bal- 
last rheostats.  The  generators  are  wound  for  75 
volts  and  designed  specially  to  give  close  voltage  reg- 
ulation over  a  wide  range  of  load,  including  100  per 
cent,  overload  during  the  time  the  second  arc  is  warm- 
ing up.  The  ampere  capacity  of  these  generators  is 
sufficient  to  accommodate  the  100  per  cent,  overload 
during  this  period.  These  motor  generators  are  built 
in  different  sizes  to  meet  the  needs  of  the  smallest  to 
the  largest  theatre,  and  are  furnished  with  induction 
motors,  single  or  polyphase,  in  all  commercial  fre- 
quencies and  voltage.  The  ballast  rheostats  insure 
constant  current  despite  variations  of  the  resistance 
in  the  arc  circuit.  This  equipment  is  designed  to 
supply  current  for  two  arcs  operating  \r\  parallel  cir- 
cuits. This  arrangement  has  a  decided  advantage, 


420 


MOTION     PICTURE     PROJECTION 


due  to  the  fact  that  one  arc  operates  entirely  inde- 
pendent of  the  other;  therefore,  if  one  arc  would  be 
"lost"  while  it  is  being  adjusted  for  the  next  reel,  the 
arc  which  is  still  operating  will  in  no  way  be  affected. 
This  means  that  the  transition  from  one  projector 
machine  to  the  other  and  from  one  reel  to  the  other 
is  accomplished  without  the  slightest  danger  of  any 
interruption  in  light  while  the  picture  is  on  the  screen. 

As  a  guide  to  those  who  contemplate  the  purchase 
of  electrical  equipment  for  motion-picture  work, 
either  in  the  studio  or  theatre,  or  to  those  who  will 
be  responsible  in  any  way  for  the  successful  operation 
of  such  equipment,  we  cannot  emphasize  too  forcibly 
the  great  importance  of  using  equipment  designed 
especially  for  this  purpose.  The  expense  involved  in 
the  production  of  the  picture  and  the  value  of  public 
opinion  to  any  theatre  owner  justify  utmost  precau- 
tion, and  any  expense  incurred  in  the  purchase  of 
equipment  which  will  insure  best  results. 


MOTION     PICTURE     PROJECTION  .    421 

WESTINGHOUSE   MOTOR-GENERATOR 

GENERAL   INFORMATION 

Unpacking.  When  uncrating  the  equipment  pro- 
tect the  various  units  against  severe  shocks  and 
blows,  especially  if  the  temperature  of  the  air  is 
very  low.  Do  not  remove  the  blocking  between  the 
generator  and  motor  frames  until  the  set  is  finally 
installed  at  its  permanent  location.  Furthermore, 
these  sets  should  never  be  moved  from  their  per- 
manent location  unless  suitable  blocking  is  placed 
between  the  motor  and  generator  frames.  This  is 
important  so  as  to  prevent  bending  the  bearings  out 
of  alignment.  Be  sure  to  protect  all  the  equipment 
from  moisture  and  make  certain  that  all  windings 
of  the  motor  and  generator  are  dry  before  subject- 
ing them  to  operating  voltage. 

Location.  All  of  the  electrical  equipment  should 
be  finally  installed  in  a  clean,  dry,  well  ventilated 
place  and  in  such  a  manner  as  to  be  easily  accessible 
for  inspection  and  cleaning.  The  room  or  enclosure 
for  the  equipment  should  be  sufficiently  well  ventil- 
ated so  that  the  air  temperature  will  never  be  in 
excess  of  104°  Fahrenheit. 

Foundation.  A  foundation  should  be  provided  for 
the  motor-generator  so  that  the  bottom  of  the  bed- 
plate will  be  approximately  two  feet  above  the  level 
of  the  surrounding  floor.  To  prevent  the  magnetic 
hum  and  vibration  of  the  set  being  transmitted  to 
the  surrounding  supports  such  as  floor  and  walls  of 
the  building,  it  is  desirable  to  build  a  vibration  and 
sound-absorbing  base. 

Such  a  base  may  be  constructed  readilv  with  solid 


422  MOTION     PICTURE     PROJECTION 

planking  two  inches  thick  and  layers  of  solid  cork 
each  layer  two  inches  thick.  Anchor  bolts  should  be 
placed  in  the  foundation  so  that  they  will  extend  a 
sufficient  distance  above  the  sound-absorbing  base  to 
permit  the  placing  of  nuts.  The  supporting  foun- 
dation should  preferably  be  made  of  hollow  concrete. 
The  cork  should  be  placed  in  two  layers  on  the  con- 
crete foundation.  On  top  of  the  cork  should  be 
placed  the  plank  frame  constructed  of  the  two  layers 
of  two-inch  plank.  The  planks  of  one  layer  should 
be  laid  at  right  angles  with  the  plank  in  the  other, 
both  layers  to  be  bolted  or  nailed  together  securely. 
The  anchor  bolts  must  be  located  so  that  they  will 
not  touch  any  portion  of  the  motor-generator  bed- 
plate. After  the  plank  frame  is  in  place  the  anchor- 
bolt  nuts  should  be  drawn  up  tight.  The  motor- 
generator  may  then  be  mounted  on  the  plank  frame 
and,  if  desirable,  the  bedplate  may  be  bolted  down 
to  the  plank  frame  as  holes  are  provided  for  this 
purpose.  If  so  desired,  heavy  felt  may  be  substituted 
for  the  cork  but  cork  is  much  more  resilient  and  will 
remain  elastic  indefinitely,  whereas  felt  will  not. 

When  constructing  the  foundation  and  sound-ab- 
sorbing base  it  is  essential  that  the  top  of  the  plank 
platform  be  made  level  so  that  the  oiling  system  of 
the  motor-generator  will  not  fail  after  the  set  is  in- 
stalled. 

Throughout  this  article,  equipments  for  two  typ- 
ical types  of  installations  will  be  considered  under 
the  captions  of  single  light,  and  two-light  equipments 
or  installations. 

The  single-light  equipment  is  required  for  each  in- 
stallation wherein  only  one  motion  picture  machine 
is  to  be  used. 


MOTION     PICTURE     PROJECTION  423 

The  two-light  equipment  is  required  for  each  in- 
stallation wherein  two  motion  picture  machines  are 
to  be  operated  alternately,  for  "change  over"  or 
"continuous  picture  service."  For  this  latter  service 
one  lamp  is  "warmed  up"  for  a  period  of  approx- 
imately one  minute  when  another  motion  picture 
machine  is  in  operation. 


Ballast  Rheostat 
EQUIPMENT    REQUIRED 

For  each  single-light  installation  a  motor-gene- 
rator and  one  ballast  rheostat  are  required,  the  con- 
trol switch  being  optional ;  whereas,  for  each  two- 
light  installation,  a  motor-generator,  two  ballast 
rheostats  and  two  control  switches  are  required. 

INSTALLATIONS 

Foreword.  For  all  cases  wherein  the  instructions 
are  equally  applicable  to  both  types  of  installations, 
namely,  two-light  and  single-light,  no  distinction  will 
be  necessary.  However,  wrhen  the  instructions  apply 


424  MOTION     PICTURE     PROJECTION 

to  only  one  of  these  types,  then  the  type  which  is 
involved  will  be  clearly  indicated. 

A  control  switch  is  a  single-pole,  single-throw  knife 
switch,  which  must  be  protected  by  a  suitable  cover 
if  mounted  on  the  frame  of  a  motion  picture  machine. 
If  the  control  switch  is  mounted  on  a  switchboard 
panel,  then  the  individual  cover  is  not  required  for 
this  switch. 

INSTALLATION 

Motor-Generator.  Install  the  motor- generator 
either  in  the  operating  booth,  or  as  near  the  booth 
as  possible. 

Motor  Starting  Equipment.  Install  the  motor 
control  equipment,  for  the  motor-generator,  in  the 
booth,  if  permissible,  or  as  near  the  booth  as  possible. 

Ballast  Rheostats.  Install  the  ballast  rheostats 
either  in  or  near  the  operating  booth.  Each  ballast 
rheostat  frame  should  be  mounted  so  that  the  three 
tie  rods,  passing  through  and  supporting  the  grids, 
are  horizontal.  This  places  the  grids  in  an  upright 
position  which  permits  a  free  circulation  of  air  ver- 
tically between  the  grids. 

Control  Switches.  The  control  switch  for  each 
ballast  rheostat  should,  preferably,  be  mounted  on 
the  frame  of  the  motion  picture  machine,  with  which 
the  ballast  rheostat  is  to  be  used,  beside  the  cut-out 
switch  connected  to  the  arc  lamp  terminals. 

Indicating  Meters.  A  suitable  direct-current  am- 
meter and  voltmeter  should  be  used  and  connected  in 
the  generator  circuit.  These  meters  should  be  in- 
stalled in  the  operating  booth,  in  a  position  where 
they  can  be  easily  seen  by  an  operator  when  he  is 
projecting  pictures. 


MOTION     PICTURE     PROJECTION  425 

Switchboard  or  Panel.  A  panel  should  be  used 
on  which  are  mounted  the  meters,  and  the  generator 
field  rheostat. 

WIRING  AND  CONNECTING  MOTOR-GENE- 
RATORS 

TYPE    CS    POLYPHASE    MOTOR 

Connect  the  motor  and  auto-starter  by  referring 
to  the  diagram  furnished  with  the  auto-starter.  If 
the  circuit  is  2-phase,  4-wire,  connect  leads  from  one 
phase  to  motor  terminals  Al  and  A2  and  leads  from 
other  phase  to  terminals  Bl  and  B2.  If  circuit  is 
2-phase,  3-wire,  connect  outside  leads  to  terminals 
Al  and  Bl  and  middle  lead  to  A2  and  B2.  If  cir- 
cuit is  3-phase  connect  any  lead  to  any  terminal. 
To  obtain  proper  direction  of  rotation  see  instruc- 


Type  "A"  Auto-Starter 


426 


MOTION     PICTURE     PROJECTION 


tions  below.  If  fuses  are  used  in  the  running  circuit 
they  should  carry  current  in  excess  of  current  in- 
dicated in  nameplate  as  follows : 

2-phase,  4-wire  circuit,  all  leads,  25  per  cent. 

2-phase,  3-wire  circuit 

outside  leads,  25  per  cent, 
middle  lead,     75  per  cent. 

3-phase,  3-wire  circuit,  all  leads,  25  per  cent. 

If  circuit-breakers  are  used  in  the  running  circuit 
they  should  be  adjusted  to  open  the  circuit  with  the 
above  overload  capacities. 

Fuses  in  the  starting  circuit  should  carry  four  to 
five  times  the  rated  current. 

TYPE   AR   SINGLE-PHASE    MOTOR 

Voltages.  This  motor  can  be  connected  for  ope- 
ration on  either  110  or  220-volt  circuits. 


I/O  VOLTS 
Diagram  of"  Connection  for  Type  AR  Motors 


MOTION     PICTURE     PROJECTION 


427 


Connections.  The  diagram  shows  the  connections. 
The  motor  is  connected  directly  to  the  line  through 
a  circuit-breaker  or  a  line  switch  and  fuses. 

TYPE    SK    DIRECT-CURRENT    MOTOR 

Connections.  Refer  to  the  diagram  and  make  the 
following  connections  for  counter-clockwise  rotation 
looking  at  the  commutator  end : 

Connect  A2  to  starting  resistors,  thence  to  +  line. 

Connect  Al  to  SI. 

Connect  S2  and  F2  to  —  line. 

Connect  Fl  to  +  line. 


Fig.  6— Diagram  of  Type  SK  Motor  Terminals 
WIRING    AND    CONNECTING    EQUIPMENTS 

Single  Light  and  Two-'Light  Equipment.  Should 
be  wired  and  connected  as  indicated  by  Fig.  12,  or 
Fig.  13,  if  a  control  switch  is  used.  If  a  control 
switch  is  not  used,  then  the  wiring  for  Fig.  12  should 
be  modified  by  omitting  the  leads  to  the  control 
switch  and  by  connecting  a  lead  from  the  lower  left- 
hand  stud  of  the  cut-out  switch  to  terminal  7  on  the 
ballast  rheostat,  instead  of  to  terminal  8.  Like- 
wise, the  wiring  of  Fig.  13  should  be  modified  by 
omitting  the  leads  to  the  control  switch  and  by  con- 
necting the  lead  from  the  lower  right-hand  stud  of 


428  MOTION     PICTURE     PROJECTION 

the  change-over  switch,  to  terminal  7  on  the  ballast 
rheostat. 

TYPE    SK    GENERATOR 

Connections.  The  diagram  and  directions  below 
show  the  connections  for  clockwise  rotation  looking 
at  the  commutator  end: 

Connect  Al  to  +  line. 

Connect  A2  and  F2  to  S2. 

Connect  SI  to  —  line. 

Connect  Fl   to  field  rheostat,  thence  to   +  line. 

MINIMUM    SIZE    OF    WIRE    FOR    INSTALLATION 

Single-light.  For  each  single-light  installation, 
wherein  the  distance  from  the  generator  terminals  to 
the  cut-out  switch  on  the  motion  picture  machine, 
measured  along  the  route  of  the  wiring  or  conduit, 
is  300  feet  or  less,  the  size  of  the  wire  is  determined 
by  the  current  to  be  carried.  (See  the  "National 
Electric  Code.")  If  the  distance  is  over  300  feet, 
the  exact  distance  should  be  referred  to  the  Com- 
pany for  recommendations  as  to  the  proper  size  of 
wire  to  be  used. 

Two-light.  The  minimum  size  of  wrire  to  be  used 
for  the  circuit,  which  must  carry  current  for  both 
lamps  for  a  two-light  installation,  is  indicated  in 
Table  No.  I,  hereinafter  given.  The  column  headed 
"Length  in  Feet  of  Circuit  Which  Must  Carry  Cur- 
rent for  Both  Arc  Lamps,"  represents  the  distance 
from  the  generator  terminals  to  the  generator 
switch,  or  to  the  point  where  the  circuit,  which  must 
carry  current  for  both  lamps,  branches  or  divides 
into  separate  circuits,  one  for  each  lamp.  The 


MOTION    PICTURE     PROJECTION  429 

distance  must  be  measured  along  the  route  of  the 
wiring  or  conduit.  If  this  distance  is  greater  than 
300  feet,  the  exact  distance  should  be  referred  to  the 
Company  for  recommendations  as  to  the  proper  size 
of  wire  to  be  used.  The  size  of  all  wires  which  carry 
current  for  one  lamp  only,  will  be  governed  by  para- 
graph 25,  but  the  distance  is  measured  along  the 
route  of  the  wiring  or  conduit  from  the  cut-out 
switch  on  each  motion  picture  machine,  to  the  gene- 
rator switch  or  to  the  point  where  the  branch  cir- 
cuit for  each  lamp  joins  the  main  generator  circuit. 
For  example,  assume  an  installation,  wherein  the 
length  of  the  circuit,  which  must  carry  current  for 
both  lamps  is  130  feet,  and  the  length  of  each  branch 
circuit  to  each  lamp  is  -30  feet,  then  if  a  2%-kilo- 
watt,  75-volt,  36.7-ampere  set  is  used,  it  will  be  ob- 
served by  reference  to  Table  No.  I,  that  No.  00  wire 
must  be  used  for  the  main  circuit,  whereas  No.  6 
wire  may  be  used  for  the  br-anch  circuit  to  each  lamp. 

For  each  two-light  installation,  wherein  the  length 
of  the  main  circuit,  which  must  carry  current  for 
both  lamps  or  wherein  the  length  of  the  branch  cir- 
cuit to  either  lamp  is  greater  than  300  feet,  a  dia- 
gram should  be  prepared  which  represents  the  wir- 
ing, and  the  length  of  each  wire  should  be  accurately 
indicated  thereon.  This  diagram  should  be  referred 
to  the  Company  for  recommendations  as  to  the 
proper  size  of  wire  to  be  used  for  each  circuit. 

Emergency  Service.  For  each  installation,  where- 
in alternating  current  is  to  be  used  for  emergency 
service,  we  strongly  recommend  that  all  wiring  and 
switches,  which  will  be  used  for  carrying  this  current 
to  each  lamp,  be  made  of  sufficient  capacity  to  carry 
the  alternating  current,  bearing  in  mind  the  fact 


430 


MOTION     PICTURE     PROJECTION 


that,  in  order  to  produce  the  same  volume,  or  candle- 
power,  of  light,  the  alternating  current  (measured 
in  amperes)  must  be  approximately  three  times  as 
great  as  the  direct  current  ordinarily  used. 

Motor  Circuits.  The  wiring  for  the  circuit  of 
each  direct-current  or  alternating-current  motor 
should  be  of  a  capacity  such  that  the  speed  of  the 
motor  will  not  be  appreciably  affected  by  the  line 
voltage  drop  at  any  load  up  to  and  including  30  per 
cent  overload  for  a  few  minutes  or  100  percent  over- 
load momentarily. 

LUBRICATION 

Before  starting,  fill  the  oil  reservoirs  with  the  best 
quality  of  clean  dynamo  oil;  overflow  plugs  must 
always  be  kept  open.  The  old  oil  should  be  with- 
drawn occasionally  and  fresh  oil  substituted.  The 
old  oil  can  be  filtered  and  used  again. 


Fig.  8 — Motor-Generator  with  Single-Phase  Alternating- 
Current  Motor 

STARTING    THE    MOTOR-GENERATOR 

General.  After  the  apparatus  is  properly  in- 
stalled and  all  wiring  is  correctly  connected,  open  all 
of  the  switches  in  the  generator  and  lamp  circuits ; 
turn  the  contact  arm,  on  the  generator  field  rheostat 


MOTION     PICTURE     PROJECTION  431 

to    the    contact   marked   "in,"    and    then    start    the 
motor  as  explained  below. 

TYPE    CS    POLYPHASE    MOTOR 

To  Start  Motor.  See  that  the  auto-starter  handle 
is  in  the  off  position.  Close  the  circuit-breaker,  if 
one  is  used,  then  close  the  main  switch.  Move  the 
auto-starter  handle  from  the  off  to  starting  position. 
When  the  motor  attains  practically  full  speed,  move 
handle  of  auto-starter  to  running  position.  Do  not 
leave  the  auto-starter  handle  in  starting  position. 

If  an  auto-starter  is  not  required,  the  starting 
switch  must  be  thrown  to  the  starting  position  until 
the  set  operates  at  almost  full  speed  and  then  the 
switch  may  be  thrown  to  the  running  position. 

TYPE   AR   SINGLE-PHASE   MOTOR 

To  Start  Motor.  Close  the  line  switch.  The 
motor  starts  as  a  repulsion  motor  with  current  flow- 
ing through  the  brushes  and  commutator.  At  nearly 
full  speed,  a  centrifugal  governor  inside  the  arma- 
ture automatically  short-circuits  the  armature  wind- 
ings, thus  causing  the  motor  to  run  as  a  squirrel- 
cage  induction  motor.  The  brushes  are  thrown  off 
by  the  end  thrust  of  the  armature.  If  the  motor 
does  not  come  to  full  speed,  which  is  shown  by  con- 
tinued sparking  at  the  brushes,  the  motor  is  over- 
loaded and  will  overheat.  Apparently  there  is  a  load 
on  the  generator.  Look  over  the  generator  circuit 
and  make  sure  that  all  load  is  removed  by  opening 
all  cut-out  switches. 


432  MOTION     PICTURE     PROJECTION 

TYPE   SK  DIRECT-CURRENT   MOTOR 

To  Start  Motor.  See  that  all  instructions  for 
connecting  and  installing  the  motor  have  been  com- 
plied with  and  that  the  handle  of  the  starter  or  con- 
troller is  in  the  "off"  position.  Close  the  line  switch 
or  circuit-breaker  and  move  the  starter  or  controller 
handle  step  by  step  to  the  running  position.  Motors 
of  less  than  10  horsepower  can  usually  be  brought 
to  full  speed  in  15  seconds,  and  the  large  motors  in 
about  30  seconds ;  the  time,  however,  varies  with  the 
torque  required.  If  the  motor  does  not  start  when 
the  third  step  is  reached,  first  open  the  line  switch 
or  circuit-breaker,  then  move  the  handle  of  the  con- 
troller to  the  "off"  position,  and  look  for  overload 
or  faulty  connections. 

INSPECTION   OF   OILING   SYSTEM 

After  the  motor-generator  is  started,  raise  the 
covers  of  all  bearings  and  see  that  all  oil  rings  are 
rotating  properly  and  carrying  oil  up  on  the  jour- 
nals. 

STOPPING  THE  MOTOR-GENERATOR 
TYPE  CS  POLYPHASE  MOTOR 

To  Stop  Motor.  Open  circuit-breaker  or  main 
switch.  Move  the  handle  of  auto-starter  to  the  off 
position.  If  neither  circuit-breaker  nor  main  switch 
is  used,  the  auto-starter  may  be  used  to  close  and 
open  the  main  circuit. 

TYPE   AR   SINGLE-PHASE   MOTOR 

To  Stop  Motor.  Open  the  line  switch  or  circuit- 
breaker. 


MOTION     PICTURE     PROJECTION  433 

TYPE   SK   DIRECT-CURRENT   MOTOR 

To  Stop  Motor.  When  a  starting  rheostat  is 
used,  open  the  line  switch  or  circuit-breaker.  Never 
force  the  starter  handle  to  the  "off"  position,  but 
allow  it  to  return  automatically. 

If  the  motor  is  to  be  shut  down  for  a  considerable 
period,  open  the  line  switch  or  breaker. 

REVERSING    MOTOR-GENERATOR 

The  rotating  element  of  the  motor-generator 
should  revolve  in  a  clockwise  direction  as  observed 
by  viewing  the  generator  end  of  the  set.  If  this  is 
not  the  case  when  the  motor  is  started,  then  the  wir- 
ing connections  for  the  motor  must  be  changed. 

TYPE   CS   POLYPHASE   MOTOR 

To  Reverse  Motor.  To  reverse  a  two-phase,  four- 
wire  motor,  the  two  leads  of  one  phase  should  be  -in- 
terchanged. To  reverse  a  two-phase,  three-wire 
motor,  the  two  outside  leads  should  be  interchanged. 
To  reverse  a  three-phase  motor,  any  two  leads  should 
be  interchanged. 

TYPE  AR   SINGLE-PHASE   MOTOR 

To  Reverse  Motor.  The  direction  of  rotation  is 
determined  by  the  position  of  the  brushes  and  is  in- 
dicated by  a  scale  on  the  rocker  ring  and  a  pointer 
on  the  front  bearing  bracket.  The  scale  consists  of 
three  lines  marked  RR,N,  and  RL,  respectively. 
When  the  rocker  ring  is  turned  so  that  the  pointer  is 
opposite  RR,  the  motor  will  run  in  a  right-hand  or 
clock-wise  direction  (facing  the  commutator)  ;  and 
when  the  pointer  is  opposite  RL,  the  rotation  will  be 


434  MOTION     PICTURE     PROJECTION 

left-hand  or  counter-clockwise.  N  is  the  neutral 
point ;  the  armature  will  not  turn  if  the  pointer  is 
opposite  this  line.  To  reverse  the  motor,  therefore, 
loosen  the  rocker  ring  set-screw  and  turn  the  rocker 
ring  until  the  pointer  is  opposite  the  line  for  the  re- 
verse direction  of  rotation. 

ADJUSTING  THE  EQUIPMENT 

After  the  set  is  running  properly,  gradually  ad- 
just the  generator  field  rheostat  until  the  potential 
between  the  generator  terminals,  as  indicated  by  a 
reliable  voltmeter,  is  approximately  75  volts. 

Single  Light.  For  single-light  equipments  (see 
Fig  12)  the  control  switch,  if  one  is  used,  should  al- 
ways be  opened  and  ballast  rheostat  contact  arm 
moved  to  extreme  right  before  striking  the  arc.  Af- 
ter the  arc  is  struck  and  the  carbons  have  been  sep- 


Fig.  9 — Motor-Generator  with   Direct-Current   Motor 

arated,  close  the  control  switch  and  then  readjust 
the  carbons  until  the  potential  across  the  arc  is  be- 
tween 50  and  55  volts,  as  indicated  by  a  reliable 
voltmeter,  the  terminals  of  which  are  connected  di- 


MOTION     PICTURE     PROJECTION  435 

rectly  to  the  carbons  in  the  lamp.  If,  under  these 
conditions,  the  current  through  the  lamp,  as  indi- 
cated by  a  reliable  ammeter,  is  less  than  required, 
and  no  greater  than  the  full  load  rating  of  the  gen- 
erator, then  the  ballast  rheostat  contact  arm  should 
be  moved  towards  the  left  until  the  proper  current 
is  obtained.  The  button  on  which  the  proper  cur- 
rent is  obtained  should  be  marked,  so  that  the  opera- 
tor can  always  place  the  arm  in  proper  position. 

Two  Light.  For  two-light  equipments  the  control 
switch  connected  to  the  ballast  rheostat  in  the  cir- 
cuit of  either  lamp,  must  always  be  opened  before 
striking  the  arc. 

With  lamp  No.  2  cut  off  the  circuit,  open  control 
switch  No.  1  and  strike  the  arc  in  lamp  No.  1.  After 
the  carbons  have  been  separated  slightly,  close  con- 
trol switch  No.  1,  move  contact  arm  of  ballast  rheo- 
stat No.  1  to  extreme  right,  and  then  readjust  the 
carbons  until  the  potential  across  the  arc  is  between 
50  and  55  volts,  as  indicated  by  a  reliable  voltmeter, 
the  terminals  of  which  are  connected  directly  to  the 
carbons  in  lamp  No.  1.  If,  under  these  conditions, 
the  current  through  lamp  No.  1,  as  indicated  by  a 
reliable  ammeter,  is  less  than  required  or  less  than 
the  full-load  rating  of  the  generator,  then  the  con- 
tact arm  of  the  ballast  rheostat  No.  1  should  be 
moved  towards  the  left  one  button  at  a  time  until  the 
proper  current  is  obtained. 

With  lamp  No.  1  cut  off  the  circuit,  open  control 
switch  No.  2,  move  contact  arm  to  extreme  right, 
and  strike  the  arc  in  lamp  No.  2.  After  the  carbons 
have  been  separated,  close  control  switch  No.  2,  and 
then  readjust  the  carbons  until  the  potential  across 


436  MOTION    PICTURE     PROJECTION 

the  arc  is  between  50  and  55  volts,  as  indicated  by  a 
reliable  voltmeter,  the  terminals  of  which  are  con- 
nected directly  to  the  carbons  in  lamp  No.  2.  If, 
under  these  conditions,  the  current  through  lamp  No. 
2,  as  indicated  by  a  reliable  ammeter,  is  less  than  re- 
quired or  less  than  the  full  load  rating  of  the  gen- 
erator, then  the  contact  arm  of  the  ballast  rheostat 
No.  2  should  be  moved  towards  the  left  one  button  at 
a  time  until  the  proper  current  is  obtained. 

OPERATING  THE   EQUIPMENT 

Single  Light.  After  the  adjustments,  specified  in 
paragraph  44,  have  been  made,  the  equipment  is  op- 
erated in  the  usual  manner,  which  needs  no  further 
explanation. 

Two  Light.  After  both  ballast  rheostats  have 
been  properly  adjusted,  as  specified  in  paragraphs 
46  and  47,  and  the  crater  in  the  positive  or  upper 
carbon  in  each  lamp  is  properly  formed,  the  entire 
equipment  is  ready  for  operation  as  hereinafter 
given. 

Insert  reel  No.  1  in  machine  No.  1 ;  open  control 
switch  No.  1 ;  strike  the  arc  in  lamp  No.  1,  and  then 
separate  the  carbons  slightly,  close  control  switch 
No.  1 ;  adjust  the  carbons  properly  and  then  project 
pictures  in  the  usual  manner. 

Reel  No.  2  should  be  inserted  in  Machine  No.  2. 
About  one  minute  before  the  end  of  reel  No.  1  is 
reached,  open  control  switch  No.  2;  strike  the  arc 
in  lamp  No.  2,  and  separate  carbons  slightly.  A  few 
seconds  before  the  end  of  reel  No.  1  is  reached,  close 
control  switch  No.  2,  and  if  necessary  make  a  final 
adjustment  of  the  carbons.  At  the  proper  time,  as 


MOTION     PICTURE     PROJECTION  437 

the  end  of  reel  No.  1  is  reached,  begin  projecting 
pictures  with  machine  No.  2,  and  cut  lamp  No.  1  off 
the  circuit. 

Reel  No.  3  should  be  inserted  in  machine  No.  1. 
About  one  minute  before  the  end  of  reel  No.  2  is 
reached,  open  control  switch  No.  1 ;  strike  the  arc 
in  lamp  No.  1,  and  adjust  the  carbons  properly.  A 
few  seconds  before  the  end  of  reel  No.  2  is  reached, 
close  control  switch  No.  1,  and  if  necessary,  make  a 
final  readjustment  of  the  carbons.  At  the  proper 
time,  as  the  end  of  reel  No.  2  is  reached,  begin  pro- 
jecting pictures  with  machine  No.  1,  and  cut  lamp 
No.  2  off  the  circuit. 

The  cycle  of  operation,  as  specified  in  paragraphs 
50,  51  and  52,  may  be  carried  out  indefinitely  at  the 
rate  of  three,  four,  or  five  1000-feet  reels  per  hour, 
without  injury  to  the  electrical  equipment,  provided 
each  lamp  does  not  require  more  than  the  full-load 
rated  current  from  the  generator  operating  at  the 
potential  of  75  volts. 

CARE  OF  MOTOR  GENERATOR 

TYPE  SK  GENERATOR  AND  MOTOR 

Commutator.  The  commutator  must  be  kept  clean 
and  the  brushes  properly  adjusted  and  fitted  to  the 
commutator.  Wipe  the  commutator  at  frequent  in- 
tervals, depending  on  the  character  of  the  service, 
with  a  piece  of  clean  canvas  cloth  free  from  lint. 
Apply  lubricant  sparingly ;  a  piece  of  paraffin  rubbed 
lightly  across  the  commutator  surface  will  furnish 
sufficient  lubrication.  No  other  attention  is  required 


438  MOTION     PICTURE     PROJECTION 

by  a  commutator  which  is  taking  on  a  polish  and 
shows  no  sign  of  wear.  A  rough,  raw,  copper-colored 
surface  should  be  smoothed  with  a  piece  of  sandpaper 
or  fine  standstone  ground  to  fit.  In  any  case  the 
final  smoothing  should  be  with  fine  (No.  00)  sand- 
paper. When  using  the  paper  or  stone  lift  the 
brushes  and  do  not  replace  them  until  all  grit  is  re- 
moved. Never  use  emery  cloth  or  emery  paper  on 
the  commutator. 

Brushes.  The  brushes  are  set  in  the  neutral  posi- 
tion at  the  factory  and  the  brackets  to  which  they 
are  attached  is  doweled  in  position.  This  adjust- 
ment should  not  be  altered,  as  it  is  correct  for  either 
direction  or  rotation. 

New  brushes  should  be  of  the  same  make  and  grade 
as  those  shipped  with  the  machine.  Brushes  should 
have  only  sufficient  clearance  in  the  box  to  slide  easily. 

TYPE  AR  SINGLE-PHASE  MOTOR 

Renewing  Brushes.  To  remove  brushes  from  the 
holder,  turn  the  rocker  ring  so  that  the  brushes  are 
brought  between  the  arms  of  the  bearing  bracket. 
Remove  the  screws  of  the  clips  that  hold  the  brushes 
in  place.  After  inserting  new  brushes,  turn  the 
rocker  ring  so  that  the  pointer  is  opposite  the  line 
for  the  proper  direction  of  rotation. 

The  front  bracket  of  the  motor  should  not  be  re- 
moved unless  unavoidable.  If  the  bracket  is  removed, 
when  replacing  make  sure  that  the  steel  pin  in  the 
brush-raising  ring  enters  the  corresponding  slot  in 
the  brushholder  casting.  Failure  to  observe  this  may 
result  in  poor  operation. 


MOTION     PICTURE     PROJECTION  439 

GENERAL   POINTERS 

Generator  Excitation.  When  a  generator  is 
started,  it  may  fail  to  build  up  its  voltage  properly. 
This  may  occur  even  though  the  generator  operated 
perfectly  during  the  preceding  run.  This  may  be 
due  to  one  or  more  of  the  following  causes : 

(a)  Slow  speed. 

(b)  Open    shunt-field   circuit,    caused   by   faulty 
connections  or  defective  field  coil  or  field  rheostat. 

(c)  Open  armature  or  commutating-field  circuit. 

(d)  Incorrect  setting  of  brushes. 

(e)  Reversed  series  or  shunt  coils. 

(f)  Poor  brush  contact  due  to  dirty  commutator 
or  brushes  sticking  in  holders. 

(g)  Loss  of  residual  magnetism. 

Examine  all  connections;  try  a  temporarily  in- 
creased pressure  on  the  brushes;  look  for  a  broken 
or  burned  out  resistor  coil  in  the  rheostat.  An  open 
circuit  in  the  field  winding  may  sometimes  be  traced 
with  the  aid  of  a  magneto  and  bell;  but  this  is  not 
an  infallible  test,  as  some  magnetos  will  not  ring 
through  a  circuit  of  such  high  resistance  as  some 
field  windings  have,  even  though  the  winding  be  in- 
tact. If  no  open  circuit  is  found  in  the  rheostat  or 
in  the  field  winding,  the  trouble  is  probably  in  the 
armature.  But  if  it  be  found  that  nothing  is  wrong 
with  the  connections  or  the  winding  it  may  be  neces- 
sary to  excite  the  field  from  another  generator  or 
some  other  outside  source.  Calling  the  generator 
that  we  desire  to  excite  No.  1,  and  the  other  machine 
from  which  current  is  to  be  drawn  No.  2,  the  follow- 
ing procedure  should  be  followed : 

Open   all   switches   and  remove   all   brushes   from 


440,  MOTION     PICTURE     PROJECTION 

generator  No.  1 ;  connect  the  positive  brushholder  of 
generator  No.  1  with  the  positive  brushholder  of 
generator  No.  2;  also  connect  the  negative  holders 
of  the  machines  together  (it  is  desirable  to  complete 
the  circuit  through  a  switch  protected  by  a  fuse  of 
about  5  amperes).  Close  the  switch.  If  the  shunt 
winding  of  generator  No.  1  is  all  right,  its  field  will 
show  considerable  magnetism.  If  possible,  reduce 
the  voltage  of  generator  No.  2  before  opening  the 
exciting  circuit ;  then  break  the  connections.  If  this 
cannot  be  done,  set  the  field  rheostat  contact  arm  of 
generator  No.  1  on  button  marked  "IN,"  then  open 
the  switch  very  closely  and  gradually  lengthen  the 
arc,  which  will  be  formed,  until  it  breaks. 

A  very  simple  means  for  getting  a  compound- 
wound  machine  to  pick  up  is  to  short-circuit  it 
through  a  fuse  having  approximately  the  current 
capacity  of  the  generator.  If  sufficient  current  to 
melt  this  fuse  is  not  generated,  it  is  evident  that  there 
is  something  wrong  with  the  armature,  either  a  short 
circuit  or  an  open  circuit.  If,  however,  the  fuse  has 
blown,  make  one  more  attempt  to  get  the  machine  to 
excite  itself.  If  it  does  not  pick  up,  it  is  evident  that 
something  is  wrong  with  the  shunt  winding  or  con- 
nections. 

If  a  new  machine  refuses  to  build  up  voltage  and 
the  connections  apparently  are  correct,  reverse  the 
field  connections;  i.  e.,  interchange  the  field  wires 
which  are  connected  to  the  positive  and  negative  ter- 
minals of  the  generator.  If  this  interchange  of  con- 
nections does  no  good,  re-establish  the  original  con- 
nections and  locate  the  fault  as  previously  advised. 


MOTION     PICTURE     PROJECTION  441 

Brushes.  All  brush  faces  resting  on  the  commuta- 
tor should  be  fitted  to  the  commutator  so  that  they 
make  good  contact  over  the  entire  area.  This  can 
be  most  easily  accomplished  after  the  brushholders 
have  been  adjusted  and  the  brushes  inserted.  Lift 
one  set  of  brushes  so  that  they  will  not  be  forced 
against  the  commutator.  Place  a  piece  of  sandpaper 
against  the  commutator  with  the  sanded  side  towards 
the  brushes.  Replace  one  brush  in  its  holder  and 
allow  the  spring  to  force  it  against  the  sandpaper. 
Draw  the  sandpaper  in  the  direction  of  rotation  un- 
der the  brush,  releasing  the  pressure  as  the  paper 
is  drawn  back,  being  careful  to  keep  the  ends  of  the 
paper  as  close  to  the  commutator  surface  as  possible 
and  thus  avoid  rounding  the  ends  of  the  brush.  After 
the  first  brush  is  properly  ground,  it  should  be  lifted 
sufficiently  to  prevent  it  being  forced  against  the 
commutator,  after  which  the  remaining  brushes  of 
the  set  may  be  similarly  ground  one  at  a  time. 

By  this  means  a  satisfactory  contact  is  quickly 
secured,  each  set  of  brushes  being  similarly  treated 
in  turn.  If  the  brushes  are  copper  plated,  their 
edges  should  be  slightly  beveled,  so  that  the  copper 
does  not  come  in  contact  with  the  commutator. 

Make  frequent  inspection  to  see  that : 

(a)  Brushes  are  not  sticking  in  holders. 

(b)  Pig-tail    shunts    are    properly    attached    to 
brushes  and  holders. 

'(c)     Tension  is  readjusted  as  the  brush  wears. 

(d)  Copper  plating  is  cut  back  so  it  does  not 
make  contact  with  commutator. 

(e)  Worn-out   brushes    are  replaced  before   they 
reach  their  wearing  limit  and  break  contact  with  the 
commutator. 


442  MOTION     PICTURE     PROJECTION 

(f)  Any  free  copper  picked  up  by  the  face  of  the 
brushes  is  removed. 

Commutator.  The  commutator  is  perhaps  the 
most  important  part  of  the  machine  in  that  it  is  most 
sensitive  to  abuse.  Under  normal  conditions,  it 
should  require  little  attention  beyond  frequent  in- 
spection. The  surface  should  always  be  kept  smooth, 
and  if,  through  extreme  carelessness,  neglect  or  acci- 
dent, it  becomes  badly  roughened,  the  armature 
should  be  removed  and  the  commutator  turned  down 
in  an  engine  lathe. 

Sparking  at  the  brushes  may  be  due  to  any  one  of 
the  following  causes : 

(a)  The  machine  may  be  overloaded. 

(b)  The  brushes  may  not  be  set  exactly  on  the 
neutral  position.     If  so,  the  neutral  should  be  de- 
termined by  running  the  machine  in  both  directions 
of  rotation  and  obtaining  the  same  voltage  at  full 
load  current  in  both  directions. 

(c)  The  brushes  may  be  welded  in  the  holders  or 
have  reached  their  limit  of  wear. 

(d)  The  brushes  may  not  be  fitted  to  the  surface 
of  the  commutator. 

(e)  The  brushes  may  not  bear  on  the  commutator 
with  sufficient  pressure. 

(f)  The  brushes  may  be  burned  on  the  ends. 

(g)  The  commutator  may  be  rough.     If  so,  it 
should  be  smoothed. 

(h)  A  commutator  bar  may  be  loose  or  may  pro- 
ject above  the  others. 

(i)  The  commutator  may  be  dirty,  oily  or  worn 
out. 

(j)  The  carbon  brushes  may  be  of  an  unsuitable 
grade. 


MOTION     PICTURE     PROJECTION  443 

(k)  The  brushes  may  not  be  equally  spaced 
around  the  periphery  of  the  commutator. 

(1)  Some  brushes  may  have  extra  pressure  and 
may  be  taking  more  than  their  share  of  the  current. 

(m)  The  contact  between  some  brush  pigtails  and 
brushholders  may  be  poor,  forcing  the  other  brushes 
to  carry  too  much  current. 

(n)    High  mica. 

(o)    Vibration  or  chattering  of  the  brushes. 

These  are  the  more  common  causes,  but  sparking 
may  be  due  to  an  open  circuit  or  loose  connection  in 
the  armature.  This  trouble  is  indicated  by  a  bright 
spark  which  appears  to  pass  completely  around  the 
commutator,  and  may  be  recognized  by  the  scarring 
of  the  commutator  at  the  point  of  open  circuit.  If  a 
lead  from  the  armature  winding  to  the  commutator 
becomes  loose  or  broken  it  will  draw  a  bright  spark 
as  the  break  passes  the  brush  position.  This  trouble 
can  be  readily  located,  because  the  insulation  on  each 
side  of  the  disconnected  bar  will  be  more  or  less 
pitted. 

The  commutator  should  run  smoothly  and  true, 
and  have  a  dark  glossy  surface. 

Heating  of  Field  Coils.  Heating  of  field  coils  may 
result  from  any  of  the  following  causes : 

(a)  Too  low  speed. 

(b)  Too  high  voltage. 

(c)  Too    great    forward    or    backward    lead    of 
brushes. 

(d)  Partial  short-circuit  of  one  coil. 

(e)  Overload. 

Heating  of  Armature.    Heating  of  armature  may 
result  from  any  of  the  following  causes : 
(a)     Too  great  load. 


444  MOTION     PICTURE     PROJECTION 

(b)  A  partial  short-circuit  of  two  coils  heating 
the  two  particular  coils  affected. 

(c)  Short-circuits  or  grounds  in  armature  wind- 
ing or  commutator. 

(d)  Bad  commutation  with  consequent  large  cir- 
culating currents  in  armature  coils  undergoing  com- 
mutation. 

Heating  of  Commutator  may  result  from  any  of 
the  following  causes : 

(a)  Overload. 

(b)  Sparking. 

(c)  Too  high  brush  pressure. 

Bucking  is  the  very  expressive  term  descriptive  of 
the  arcing  between  adjacent  brush  arms.  In  general, 
bucking  is  caused  by  excessive  voltage  between  com- 
mutator bars,  or  by  abnormally  low  surface  resist- 
ance on  the  commutator  between  brushholders  of  op- 
posite polarity.  Any  condition  tending  to  produce 
poor  commutation  increases  the  danger  of  bucking. 
Among  other  causes  are  the  following : 

(a)     Rough  or  dirty  commutator, 
(b)    A  drop  of  water  on  the  commutator  from  the 
roof,  leaky  steam  pipes  or  other  source. 

(c)  Short-circuits  on  the  line  producing  exces- 
sive overloads. 


MOTION     PICTURE     PROJECTION 


445 


MOTION   PICTURE   EQUIPMENT— SINGLE   LIGHT 
Schematic  Connections 

Motion  Picture  Machine 


Control  Switch 


Ballast 
Resistor 


Generator 
Switch 


Meg,  Gen 
Terminal 


Grouncl 

Series  Field- 
Corn m.  Fie/d- 


-V\AA/\T 

Shunt  He/d 

Fig.  12 


446 


MOTION     PICTURE     PROJECTION 


MOTION   PICTURE   EQUIPMENT— SINGLE   LIGHT 
Schematic  Connections;  Panel  Provided  for  Emergency  Service 

Motion  Picture  Machine 


Control  Switch 


Generator 


Neg.  Gen^ 
Terminal 

Ground 

Series  field- 
Comm.  field- 


ShvntF/e/d 

Fig.  13 


MOTION     PICTURE     PROJECTION  447 


'A   Pocket  Reference  Book 

FOR 

Managers  and  Projectionists' 

By  JAMES  R.  CAMERON 


Price  One  Dollar 
THEATRE  SUPPLY  COMPANY 

124  WEST  45xn  STREET  NEW  YORK  CITY 


448  MOTION     PICTURE     PROJECTION 


MEASURING  WIRE 

First  scrape  off  the  insulation,  then  take  one 
strand  of  wire  and  insert  it  in  the  smallest  slot  pos- 
sible on  a  Brown  and  Sharp  wire  gauge.  Find  out 
(by  using  wire  table)  the  number  of  circular  mils 
contained  in  the  one  strand,  then  multiply  the  num- 
ber of  circular  mils  by  the  number  of  strands  in 
the  wire,  then  refer  to  wire  table  on  page  449,  and 
find  the  nearest  corresponding  number  of  circular 
mils,  look  opposite  to  find  what  size  wire  you  have. 

For  instance,  suppose  we  are  going  to  measure 
a  length  of  stranded  wire,  we  first  take  one  strand 
and  measure  with  B.  &  S.  gauge.  Let  us  take  it  for 
granted  that  it  measures  No.  14,  now  find  out  by 
using  table  on  page  76  how  many  circular  mils 
there  are  in  a  No.  14  wire — 4,107;  next  count  the 
strands  in  the  wire  and  say  we  count  7;  then,  by 
multiplying  the  4,107  by  7  we  will  find  the  circular 
mils  in  the  whole  wire  or  4,107  X  7  =  28,749  circu- 
lar mils  in  the  whole  wire.  Now  find  the  nearest 
corresponding  number  to  28,749  in  circular  mil  table 
and  we  find  it  is  26,250,  and  looking  over  to  the 
first  column  we  find  this  to  be  a  No.  6  wire. 


MOTION     PICTURE     PROJECTION 


449 


CARRYING  CAPACITY  OF  COPPER  WIRE 


B.  &  S.  Gauge 

Circular  Mils 

Table  A 
Rubber  Insulat. 
Ampere 

Table  B 
Other  Insulats. 
Ampere 

18 

1,624 

3 

5 

16 

2,583 

6 

8 

14 

4,107 

15 

16 

12 

6,530 

17 

23 

10 

10,380 

24 

32 

8 

16,510 

35 

46 

6 

26,250 

50 

65 

5 

33,100 

54 

77 

4 

41,740 

65 

92 

3 

52,630 

76 

110 

2 

66,370 

90 

131 

1 

83,690 

107 

156 

0 

105,500 

127 

185 

00 

133,100 

150 

200 

000 

167,800 

177 

.262 

0000 

211,600 

210 

312 

200,000 

200 

300 

300,000 

270 

400 

400,000 

330 

500 

500,000 

390 

590 

600,000  - 

450 

680 

700,000 

500 

760 

800,000 

550 

840 

900,000 

600 

920 

1,000,000 

650 

1,000 

1,100,000 

690 

1,070 

1,200,000 

730 

1,150 

1,300,000 

770 

1,220 

1,400,000 

810 

1,290 

1,500,000 

850 

1,360 

1,600,000 

890 

1,430 

1,700,000 

930 

1,490 

1,800,000 

970 

1,550 

1,900,000 

1,010 

1,610 

2,000,000 

1,050 

1,670 

The  lower  limit  is  specified  for  rubber-covered  wires  to  pre- 
vent gradual  deterioration  of  the  high  insulations  by  the  heat 
of  the  wires,  but  not  from  fear  of  igniting  the  insulation.  The 
question  of  drop  is  not  taken  into  consideration  in  the  above 
tables. 


450  MOTION    PICTURE     PROJECTION 


POINTS  TO  REMEMBER 

To  find  the  positive  or  negative  polarity  when 
connected  up,  strike  the  arc  and  let  same  burn  for 
a  second  or  two,  then  throw  off  the  switch  and  look 
to  see  which  of  the  carbons  cool  off  first.  Whichever 
remains  red  the  longest  is  the  positive  and  this 
should  always  be  the  carbon  in  the  top  jaw  of  lamp. 

If  you  find  that  the  lower  carbon  remains  red 
longer  than  the  top,  then  your  lamp  is  burning  up- 
side down,  or  in  other  words,  the  positive  line  is 
connected  to  the  lower  jaw  instead  of  the  top.  This 
can  be  remedied  by  changing  the  wires  at  arc,  wall- 
switch,  or  table-switch. 

Should  both  carbons  remain  red  the  same  length 
or  time  you  have  alternating  current. 

The  Department  of  Water  Supply,  Gas  and  Elec- 
tricity call  for  the  use  of  link  fuses  in  the  operating 
booth  on  the  machine  line.  Cartridge  fuses  are  not 
allowed. 

Always  see  that  all  electrical  connections  are  tight 
and  that  lamphouse,  etc.,  is  free  from  grounds. 

Examine  the  lamp  leads  every  so  often.  Remember 
that  copper  oxidizes  when  overheated. 

See  that  you  have  enough  carbon  in  holders  to  run 
the  reel  through. 

When  buying  or  fitting  condensers  and  mounts  for 
same,  remember  to  leave  room  in  mounts  for  the 
expansion  and  contraction  of  condensers.  Remember 
that  cold  draughts  will  break  your  condensers. 

The  joint  resistance  of  two  conductors  connected 
in  parallel  is  equal  to  the  product  of  the  resistances, 
divided  by  their  sum. 


MOTION    PICTURE     PROJECTION  451 

The  joint  resistance  of  any  number  of  resistances 
connected  in  parallel  is  the  reciprocal  of  the  sum  of 
the  reciprocals.  (The  reciprocal  of  a  number  is  1 
divided  by  that  number.) 

The  total  resistance  of  a  number  of  resistances  in 
series  is  equal  to  the  sum  of  all  of  them. 

The  heating  of  the  rheostat  is  proportional  to  the 
square  of  the  current  it  carries. 

Drop  in  voltage  is  proportional  to  the  product  of 
the  current  and  resistance  for  a  direct  current  cir- 
cuit, and  the  product  of  current  and  impedance  for 
an  alternating  current  circuit. 

To  find  the  size  of  a  picture  obtainable  under  given 
conditions  and  lens.  Multiply  distance  from  center 
of  lens  to  screen  by  one  dimension  of  slide  or  film 
and  divide  by  equivalent  focal  length  of  lens,  taking 
all  measurement  in  inches. 

To  find  focal  length  of  lens  for  a  given  slide  or 
film  to  produce  a  given  size  of  picture.  Multiply 
slide  or  film  dimension  by  length  of  throw  and  divide 
by  dimension  of  picture.  All  measurements  in  inches. 

To  find  length  of  throw  needed  to  obtain  a  certain 
size  of  picture.  Multiply  required  picture  dimensions 
by  focal  length  of  lens  and  divide  by  slide  or  film 
dimension. 

One  foot  of  film  contains  16  pictures. 

One  turn  of  the  crank  runs  off  1  foot  of  film. 

Resistance  of  any  conductor  is  equal  to  its  length 
in  feet  divided  by  the  area  in  circular  mils,  multiplied 
by  the  resistance  per  mil  foot  which  is  10.8  ohms. 

Resistance  of  all  metals  increase  with  an  increase 
of  temperature. 


452  MOTION     PICTURE     PROJECTION 

Resistance  of  insulating  material  and  carbon  de- 
crease with  an  increase  of  temperature. 

To  set  the  flicker  shutter,  loosen  up  the  set  screw 
so  that  shutter  revolves  freely  on  the  shaft,  now 
turn  shutter  till  single  set  screw  is  in  groove  of  shaft 
and  then  tighten,  now  loosen  the  two  screws  on  the 
collar  and  open  the  gate  of  machine.  Turn  the 
balance  wheel  till  you  see  that  the  intermittent 
movement  is  just  about  to  revolve,  then  the  large 
blade  of  shutter  should  just  be  coming  up  to  cover 
lens,  and  should  be  so  fixed  that  the  blade  of  shutter 
is  covering  the  front  of  lens  as  long  as  the  intermit- 
tent sprocket  is  in  motion. 

Another  way  to  set  it  is  as  follows :  Turn '  the 
balance  wheel  till  two  teeth  of  the  intermittent 
sprocket  have  passed  a  given  point;  this  represents 
one-half  of  a  picture  or,  in  other  words,  that  the 
picture  has  completed  one-half  of  its  movement,  now 
set  the  large  blade  of  the  flicker  shutter  dead  over 
the  front  of  lens. 

Always  keep  carbon  holders  clean  so  that  carbons 
make  good  contact. 

Always  have  a  spare  belt  (driving  and  take-up) 
near  at  hand. 

Keep  your  fingers  off  the  glass  surfaces  of  lenses. 

Oil  machine  often  a  little  at  a  time,  keep  oil  off 
the  floor  of  the  booth. 

Keep  oil  off  the  friction  discs. 

Never  use  oil  on  the  arc  lamp.    Use  graphite. 

Renew  motor  brushes,  whenever  necessary,  and 
keep  grease  cups. filled. 


MOTION     PICTURE     PROJECTION"  453 


TABLE  OF  RESISTIVITIES  AND  CONDUCTIVITIES  OF 
METALS 

Specific  Resistance      Relative 

in  Microhms  Conductivity 

Per  Cubic  at  Zero, 

Substances                                      Centimeter  Centigrade 

Pure  Silver 1.49  100.00 

Refined  Copper 1.59  99.90 

Pure  Gold  (unalloyed) 2.04  86.65 

Aluminum  (annealed) 2.89  63.09 

Swedish  Iron 10.08  16.00 

Platinum  (pure) 11.00  10.60 

Lead   19.63  8.88 

German  Silver 30.00  7.70 

Mercury 94.30  1.60 


TABLE   OF   BRIGHTNESS   VALUES   IN   CANDLE- 
POWER  PER  SQUARE  INCH 

White  paper  in  bright  sunlight 15 

Coal  gas  flame 3 

Kerosene  flame 0.9 

Acetylene  flame 30-60 

Welsbach  mantle  (mean) 80 

Carbon  filament 750 

Tungsten  filament  (ordinary  vacuum  practice) 1,000 

Tungsten  filament  (ordinary  gas-filled  practice)  .2,000-7,000 

Nearnst  lamp  glower  (max.) 3,000 

Lime  light 2,000 

Tungsten  filament  (special  practice) 24,000 

The  sun  at  mid-day 660,000 


454 


MOTION    PICTURE    PROJECTION 


HJS i| £ 

nuiH 


^tlsll 


MOTION    PICTURE     PROJECTION 


455 


VOLTS  LOST  ON  COPPER  WIRE 

Table  of  Volts  lost  or  drop  per  ampere  per  1,000  feet  of  con- 
ductor. (Calculated  by  E  —  I  X  R-  Formula  (29).)  Copper 
wire,  B.  &  S.  gauge  (70°  F.). 


Size, 
B.&S. 

Volts  Drop 
per  Ampere 
per  1,000  Ft. 

Size, 
B.&S. 

Volts  Drop 
per  Ampere 
per  1,000  Ft. 

0000 

.0493 

17 

5.088 

000 

.0621 

18 

6.415 

00 

.0783 

19 

8.089 

0 

.0987 

20 

10.20 

1 

.1242 

21 

12.86 

2 

.1570 

22 

16.22 

8 

.1980 

23 

20.45 

4 

.2496 

24 

25.79 

5 

.3148 

25 

82.52 

6 

.8970 

26 

41.01 

7 

.5006 

27 

51.72 

8 

.6312 

28 

65.21 

9 

.7958 

29 

82.23 

10 

1.040 

30 

103.7 

11 

1.266 

31 

130.7 

12 

1.696 

32 

164.9 

13 

2.012 

33 

207.9 

14 

2.637 

34 

262.2 

15 

8.200 

35 

830.6 

16 

4.035 

86 

416.8 

456 


MOTION     PICTURE     PROJECTION 


SIZE    OF   WIRES   FOR    MOTORS    OF    DIFFERENT 
HORSE  POWER 

DIRECT    CURRENT 


110  Volts 


220  Volts 


H.  P. 

Full-load 
Current 

Size  of 
Wire 
Mains 

Size  of 
Wire 
Branches 

Full-load 
Current 

Size  of 
Wire 
Mains 

Size  of 
Wire 

Branches 

1 

8 

14 

14 

4 

14 

14 

2 

15 

14 

12 

8 

14 

14 

3 

23 

10 

8 

12 

14 

14 

4 

30 

8 

6 

15 

14 

12 

5 

38 

6 

6 

19 

12 

10 

7.5 

56 

5 

4 

28 

8 

8 

10 

75 

3 

1 

38 

6 

6 

SIXGLE-PHASE 


I 

12 

12 

6 

14 

2 

23 

g 

11 

12 

3 

33 

6 

16 

10 

4 

44 

4 

22 

8 

53 

3 

26 

6 

THREE-PHASE 


1 

3 

14 

14 

2 

5 

14 

14 

3 

8 

14 

14 

4 

10 

14 

14 

5 

13 

14 

12 

7  5 

19 

12 

8 

10 

26 

8 

6 

MOTION     PICTURE     PROJECTION 


457 


CONVERSION  TABLES 


(1)  WATTS  TO  HORSE  POWER 


Watts 

Horse  Power 

Kilowatts 

Horse  Power 

1 

.0014 

.5 

.670 

5 

.0067 

.75 

1.005 

10 

.0134 

1.0 

1.34 

20 

.0268 

2.0 

2.68 

25 

.0335 

3.0     . 

4.02 

30 

.0402 

4.0 

5.36 

40 

.0536 

5.0 

6.70 

50 

.067 

6.0 

8.04 

75 

.100 

7.0 

9.38 

100 

.134 

8.0 

10.0 

200 

.268 

9.0 

12.1 

250 

.335 

10.0 

13.4 

(2)   HORSE  POWER  TO  WATTS 


Horse  Power 

Watts 

Horse  Power 

Kilowatts 

& 

46.62 

4 

2.984 

% 

93.25 

5 

3.730 

y* 

186.5 

6 

4.476 

ya 

373.0 

7 

5.222 

% 

559.5 

8 

5.968 

i 

746.0 

9 

6.714 

2 

1492.0 

10 

7.460 

3 

2338.0 

20 

14.920 

458 


MOTION     PICTURE     PROJECTION 


POWER  REQUIRED  FOR  DRIVING  FANS 


Diameter 
of 
,      Blades 

Power 
required 
in  Watts 

Approx.  cub. 
feet  of  Air 
moved 
per  hour 

Average 
Speed  in 
Revolutions 
per  minute 

12  inches 

50 

60,000 

1,000 

15      " 

70 

72,000 

900 

18       " 

100 

120,000 

750 

24       " 

200 

800,000 

600 

30       " 

350 

420,000 

500 

36       « 

450 

720,000 

450 

42       " 

550 

840,000 

360 

48       " 

650 

1,000,000 

300 

SPARKING  DISTANCES  IN  AIR 


Volts 

Distance 
(Inches) 

Volts 

Distance 
(Inches) 

6,000 

.225 

60,000 

4.65 

10,000 

.47 

70,000 

5.85 

20,000 

1.00 

80,000 

7.1 

80,000 

1.625 

100,000 

9.6 

35,000 

2.00 

130,000 

12.95 

46,000 

2.95 

150,000 

15.00 

MOTION     PICTURE     PROJECTION 


459 


Inches  to  millimetres 

Centimetres  to  inches 

Inches 

mm. 

cm. 

cm. 

inches 

t"&     = 

1,58 

— 

0.16 

1 

= 

3A 

y%  ~ 

8,17 

— 

0,32 

2 

— 

i§ 

y*  — 

6,35 

= 

0,63 

3 

— 

1^ 

•^8      — 

9,5 

-— 

0,95 

4 

as 

!•& 

y2    = 

12,7 

== 

1,27 

5 

— 

Hi 

y%  — 

16,9 

= 

1,59 

6 

~— 

%y& 

y±  = 

19 

— 

1,9 

7 

— 

2^ 

^8      — 

22,2 

— 

2,2 

8 

— 

8^ 

i  — 

25,4 

—  : 

2,54 

9 

—  • 

8& 

2     = 

50,8 

== 

5,08 

10 

— 

8il 

8     = 

76,2 

— 

7,6 

11 

— 

4^ 

4     = 

101,6 

— 

10,1 

12 

rr: 

4H 

5     = 

127 

— 

12,7 

18 

as 

5*A 

6     = 

152 

— 

15,2 

14 

E— 

&l/2 

7     = 

177 

— 

17,7 

15 

a- 

5H 

8     = 

208 

= 

20,3 

16 

a- 

a* 

9     = 

229 

= 

22,9 

17 

as 

10     = 

254 

—  • 

25,4 

18 

— 

7-^ 

11     = 

280 

— 

28 

19 

— 

7^ 

12     = 

304 

= 

80,4 

20 

as 

The  above  values  are  cor- 

The above 

values  are  cor- 

rect  to  y2 

mm. 

rect  to  Jz  i°- 

460 


MOTION     PICTURE     PROJECTION 


TABLE  OF  ELECTRICAL  UNITS 


Name  of 
Unit 

Usually 
Expressed 

Repre- 
senting 

Equivalent  to 

Volt 

E.M.F.E. 

Pressure 

Amperes  X  Ohms 

Ampere 

C.;  A. 

Current 

Volts  -f-  Ohms 

Ohm 

R. 

Resistance 

Volts  -4-  Amperes 

Watt 

W. 

Power 

Amp.X  Volt;  VT48  H.P. 

Kilowatt 

K.W. 

Power 

1,000  Watts;  iy3  H.P. 

Kilowatt- 
Hour 
Horse  Power 

K.W.H. 
H.P. 

Work 
Power 

1,000  Watt-hours 
746  Watts 

Horse  Power 
Hour 

H.P. 
Hour 

Work 

T46  Watt-hours 

MOTION     PICTURE     PROJECTION 


461 


CAPACITY  OF  FUSE  WIRES 


Dia.  in 
1/1,000  in. 


48 

36 

28 

22 

18 

15 

12 

10 

9 

7 

6 

4 


Copper 
Amperes 


286.0 

166.0 

105.0 

70.0 

48.0 

33.5 

24.8 

18.4 

14.1 

11.5 

9.0 

6.8 

4.7 

3.5 


Wires  Tin 
Amperes 


46.0 

26.0 

17.0 

11.2 

7.7 

5.4 

4.0 

3.0 

2.8 

1.8 

1.5 

1.0 

.76 

.55 


Lead 
Amperes 


38.0 
22.2 
14.0 
9.4 
6.5 
4.5 
3.35 
2.5 
2.0 
1.5 
1.2 
.9 
.64 
.45 


REFLECTING  POWER  OF  WALLS,  PAPER,  ETC. 

Black  Cloth 1  per  cent. 

Chocolate  Paper    5  per  cent. 

Dark  Red   12  per  cent. 

Dark  Brown  '. . .  13  per  cent. 

Blue 25  per  cent. 

Yellow 40  per  cent. 

White  Glazed 75  per  cent. 

APPROXIMATE  LOSS  OF  LIGHT  DUE  TO  ARC 
LAMP  GLOBES 

Clear  Glass  12  per  cent. 

Light  Ground  Glass  30  per  cent. 

Heavy  ditto 45  per  cent. 

Thin  Opal 45  per  cent. 

Heavy  Opal    60  per  cent. 

Holoplane  (cut  glass) 15  per  cent. 


462 


MOTION     PICTURE     PROJECTION 


A  comparison  of  the  following  tables  will  show  the 
superiority  of  using  direct  current  from  the  basis  of 
energy  consumed  and  greater  candle-power  from  the 
tained.  It  is  regrettable  that  the  quality  of  the  light 
from  direct  current  cannot  be  shown  in  this  table  of 
comparative  results. 

Comparison  of  candle-powers  obtained  from  alter- 
nating and  direct  current  circuits  with  a  given  cur- 
rent consumption: 


Arc 
amperes 

Candle-power 
using  A.  C. 

Candle-power 
using  D.  C. 

20 
25 
30 
40 
50 
60 

624 
894 
1,700 
1,830 
4,566 
4,650 

4,900 
6,220 
8,750 
12,000 
16,500 

WATTS  CONSUMED  PER  HOUR  FOR  A  GIVEN 
CANDLE-POWER 


Candle- 
power 

I.  C.  with 
resistance 

A.  C.  with 
resistance 

A.  C.  with 
economizer 

A.  C.  with 
rectifier 

4,000 

1,900 

5,800 

1,700 

1,300 

5,000 

2,250 

6,900 

2,200 

1,500 

6,000 

2,600 

.  . 

1,800 

7,500 

3,100 

.  . 

.  . 

2,250 

10,000 

3,800 

2,700 

12,000 

4,400 

3,20  J 

16,500 

5,500 

3,900 

MOTION    PICTURE     PROJECTION 


463 


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MOTION     PICTURE     PROJECTION 


465 


USEFUL  EQUIVALENTS  FOR  ELECTRIC  HEATING 
PROBLEMS 


Unit. 

Equivalent  Value  In   Other 
i                    Units. 

Unit. 

Equivalent  Value  In   Other 
Unita. 

1,000  Watt  hours 
1.34  horse  power  hours 
2,654,200  ft.    Ibs. 
3,600,000  joules 
3,412  heat  units 

1 
ft.  Ib.  = 

1.356  joules 
.1383  k.  g.  m. 
.000000377  K.   W.   hour 
.0001285   heat   units 
.0000005   H.   P.    hour 

1 
K.  W. 
Hour  = 

367,000  kilogram  metres 
.  229  Ibs.  coal  oxidized  with 
perfect  efficiency 
3.53  Ibs.  water  evaporated 
at  212°  P. 
22.75  Ibs.    of  water  raised 
from   62°  to  212°  F. 

1 

Watt  = 

1  joule  per  second 
.00134   H.    P. 
.001    K.    W. 
3.412  heat  units  per  hour 
.7373  ft.  Ibs.   per  second 
.003  Ibs.   of  water  evap- 
orated,   per   hour 
44.24  ft.  Ibs.  per  minute 

1 
H.  P. 

Hour  = 

.746  K.  W.  hour 
1,930,000  ft.  Ibs. 
2,545  heat  units 
273,740  k.  g.  m. 
.  1  75  Ibs.  coal  oxidized  with 
perfect  efficiency 
2.64  Ibs.  water  evaporated 

1  Watt  per 
Sq.  In.  = 

8.19  thermal  units  per  sq. 
ft.  per  minute 
120°   F.    above  surrounding 
air   (Japanned  cast 
iron   surface) 
66°    C.    above   surrounding 
air   (Japanned  cast 
iron  surface) 

at  212°  F. 
17.0  Ibs.  water  raised  from 
62°  F.  to  212°  F. 

1055  Watt   seconds 
778  ft.  Ibs. 
.252  calorie   (Kg.   d.) 
107.6  kilogram  metres 

.   1 
K.  W.  = 

1,000  Watts 
1.34   H.   P. 
2,654,200  ft.   Ibs.   per  hour 
44.24  ft.  Ibs.  per  minute 
737.3  ft.   Ibs.  per  second 

Heat  Unit  = 

.000293  K.  W.   hour 
.000393  H.  P.  Hour 
.0000688    Ibs.    coal    oxi- 
dized 
.001036  Ibs.  water  evap- 
orated at  212°  F. 

3,412  heat  units  per  hour 
36.9  heat  units  per  minute 
9.48  heat  units  per  second 

1  Heat  Unit 
Per  Sq.  Ft. 
Per  Minute  = 

1221  Watts  per  sq.  inch 
.0176  K.   W. 
.0296  H.   P. 

per  hour 
2.58  Ibs.  water  evaporated 
per  hpur  at  212°  F. 

1  Kilogram 
Metre  == 

7.23%   ft.    Ibs. 
.00000366  H.  P.  hour 
.00000272  K.  W.   hour 
.0093  heat  units 

1 
H.  P.  = 

746  Watts 
.746   K.   W. 
33.000  ft.  Ibs.  per  minute 
550  ft.  Ibs.  per  second 
2,545  heat  units  per  hour 
42.4  heat  units  per  minute 
.707  heat  units  per  second 
.175    Ibs.    coal    oxidized 
per  hour 
2.64  Ibs.  water  evaporated 
per  hour  at  212°  F. 

1  Ib.  Bitu- 
minous Coal 
Oxidized 
with  perfect 
efficiency  ^ 

14,544  heat  units 
1.11   Ibs.   Anthracite  coal 
oxidized 
2.5  Ibs.  dry  wood  oxidized 
21  cu.  ft.  illuminating  gas 
4.26   K.    W.    hours    (the- 
oretical value) 
5.71    H.    P.    hours    (the- 
oretical  value) 
11,315,000  ft.  Ibs.    (theoret- 
ical value) 
15  Ibs.    of  watei    evapo- 
rated at  212°  F. 

1 
Joule  == 

1  Watt  second 
.00000278  K.   W.  hour 
.102  k.   g.  m. 
.0009477  heat  units 
.7373  ft.  Ibs. 

1  Ib.  Water 
Evaporated 
212°  F.  = 

.283  K.  W.  hour 
.379  H.  P.   hour 
965.7  heat  units 
103,900  k.  g.  m. 
,019,000   joules 
751,300  ft.  Ibs. 
.0664  Ibs.  of  coal  oxidized 

466 


MOTION     PICTURE     PROJECTION 


RECAPITULATIONS 

DEFINITIONS  OF  PRACTICAL  ELECTRICAL  UNITS 


I  J   "• 

Quantities 
to  be 
Measured. 

Synonyms. 

Sym- 
bol. 

Name  of 
Practical 
Unit. 

Comparative 
Values. 

REMARKS 
Fundamental  or  absolute  51 
C.  G.  S.  Units  are: 
Centimeter   (C)   for  Length. 
Gramme   (G)    for  Mass. 
Second  S   (8)   for  Time. 

Current. 

Strength. 
Intensity. 
Rate  of  Flow. 
Coulomb  per 
Sec. 
Volume    (ob- 
solete). 

I 

Ampere. 

Coulombs  -j- 
Seconds. 
Volts  -i- 

Ohms. 

One  Ampere  deposits  .0003- 
286  gramme,  or  .004991 
grain  of  copper  per  sec- 
ond on  the  plate  of  a 
copper  voltmeter. 

Quantity. 

Ampere-Sec- 
ond. 

Q 

Coulomb. 

Amperes  X 
Seconds. 

One  hour  =  3,600  seconds; 
hence  one  ampere-hour  = 
3,600  ampere-seconds,  or 
=  3,600  coulombs. 

Electromo- 
tive  Force. 
Difference 
of  Potential. 

Pressure 
Tension. 

EMF 

or  E 

Volt. 

Amperes  X 
Ohms. 
Joules  -:- 
Coulombs. 

One  volt  =  .933  standard 
Daniell  cell  (zinc  sul- 
phate of  a  density  of  1.4 
and  copper  sulphate  of  a 
density  of  1.1). 

Resistance. 

E 

Ohm. 

Volts  -f 
Amperes. 

One  legal  ohm  is  the  resist- 
ance of  a  column  of  pure 
mercury,  1  square  milli- 
meter in  section  and  106 
centimeters  long,  at  "Cen- 
tigrade. 1  true  ohm  — 
1.00283  legal  ohms. 

Capacity. 

M 

Farad. 

Coulombs  -i- 
Volts. 

[i    i  : 

The  microfarad,  one  -  mil- 
lionth of  a  farad,  has 
been  generally  adopted  as 
a  practical  unit;  the 
farad  is  too  large  a  unit 
for  practical  use. 

Power 
Activity. 

Electrical 
H.    P. 
Rate  of  doing 
Work. 
Effect. 
Work  -i-  Time. 

P 

orPw. 
or  HP 

Watt. 
(Volt-  am- 
pere) . 

Volts  X 
Amperes. 
(Amperes)  X 
Ohms. 
(Volts)  -:- 
Ohms. 
Joules  -f- 
Seconds. 

One  watt  =  1/746  electrical 
horse    power. 
t)ne   electrical   horse   power 
=  volts  X  amperes 

746 
One   electrical   horse  power 
=  (amperes)  x  ohms 

746 
One   electrical   horse   power 
=    (volts) 

746  ohms 

Work. 
Heat. 
Energy. 

Power  X 
Time. 

W 

or  Wj. 

Joule 
(Volt-cou- 
lomb.) 

Watts  X 
Seconds. 
Volts  X 
Coulombs. 
(Amperes)  X 
Ohms  X  Sec- 
onds. . 
(Volts)  X 
Seconds  -f- 
Ohms. 

One  joule  is  the  work  done 
or    heat    generated    by    a 
watt  in  a  second. 
One  joule  is  the  heat  neces- 
sary to  raise  .238  gramme 
of   water    1°    C.  ;   or   one 
joule  =  .238    calorie    or 
therm.     One  Joule  =.7375 
foot-pound    in    a   second. 

MOTION     PICTURE     PROJECTION  467 


COPY  OF  THE  RULES 

ISSUED  BY  THE  DEPARTMENT  OF  WATER  SUPPLY, 
GAS  AND  ELECTRICITY,  NEW  YORK  CITY 

The  Operator's  License  and  copy  of  these  rules  shall  be 
displayed  in  a  conspicuous  place  in  the  booth  while  the  public 
is  in  or  has  access  to  the  premises. 

No  operator  shall  conduct  an  exhibition  except  where  to  his 
knowledge  a  permit  or  license  of  the  department  of  licenses  is 
exhibited  on  the  premises. 

The  apparatus  and  its  construction  shall  be  tested  by  the 
operator  prior  to  each  performance.  No  defective  apparatus, 
or  apparatus  of  a  type  not  approved  by  this  department  shall 
be  operated.  No  apparatus  with  a  lamp  served  with  oxy- 
hydrogen  or  acetylene  gas  shall  be  approved. 

It  is  forbidden  to  overfuse  (see  electrical  code,  section  418  of 
the  Code  of  Ordinances)  or  to  make  any  electrical  connections 
not  sanctioned  by  the  aforesaid  chapter  (see  section  438). 

The  operator  shall  report  promptly  every  defect  in  the  ap- 
paratus or  its  connection,  the  correction  of  which  he  is  unable 
to  secure. 

Badly  torn  films  shall  not  be  used  and  their  presence  in  the 
booth  shall  be  reported  as  soon  as  practical. 

The  booth  at  all  times  shall  be  kept  clean.  No  pieces  of  film 
or  loose  combustible  material  shall  be  allowed  to  remain  in  the 
booth,  unless  kept  in  a  metal  box  provided  with  a  close  fitting 
cover  constructed  without  the  use  of  solder. 

The  door  of  the  booth  shall  be  kept  closed  while  the  public 
has  access  to  the  premises. 

No  person  shall  be  allowed  in  the  booth  except  the  manager 
or  owner  of  the  premises,  a  licensed  operator,  a  person  spe- 
cially authorized  by  the  commissioner  in  writing,  or  any  duly 
accredited  officer  of  the  city. 

The  interior  of  the  booth  shall  remain  readily  accessible  to 
the  persons  mentioned  in  the  foregoing  section.  The  door  of 
the  booth  shall  not  be  latched  on  the  inside  nor  the  handle  re- 
moved from  the  outside,  nor  shall  any  signalling  device  be  per- 
mitted which  is  operated  from  the  front  of  the  house. 

No  film  other  than  that  on  the  machine  or  on  the  rewinder 
shall  be  exposed  in  the  booth  at  any  time. 

No  smoking  is  permitted  in  the  booth  at  any  time. 


468  MOTION     PICTURE     PROJECTION 

No  matches,  fire  or  open  light  is  permitted  in  the  booth 
while  the  public  is  on  or  has  access  to  the  house  or  premises. 

Every  fire,  together  with  the  apparent  cause  thereof,  shall  be 
promptly  reported. 

Advance  report  shall  be  made  of  the  installation  of  a  moving 
picture  machine  for  a  one  night  exhibition. 

The  apparatus  shall  at  all  times  be  in  charge  of  a  licensed 
operator. 

It  is  forbidden  to  operate  while  under  the  influence  of  liquor 
or  drug  or  to  read  while  operating. 

Certificates  shall  not  be  loaned  or  transferred. 


MOTION     PICTURE     PROJECTION  469 


COMMONWEALTH  OF  PENNSYLVANIA 
Moving  Picture  Act  of  May  1,  1909 

Section  1.  That  it  shall  be  unlawful  for  any  person,  firm, 
association,  or  corporation  to  erect,  set  up,  construct,  maintain, 
or  use  any  permanent  booth  or  enclosure  for  the  purpose  of 
operating  therein  moving  picture  machines,  unless  they  are 
built,  erected  and  constructed  as  follows: 

Size:  All  permanent  booths  or  enclosures  to  be  at  least  seven 
feet  high,  the  floor  space  to  vary  according  to  the  number  of 
machines  in  booths  or  enclosures,  as  follows: 

One  picture  machine,  six  feet  by  eight  feet. 

One  picture  machine  and  one  stereopticon,  nine  feet  by  eight 
feet. 

Two  picture  machines  and  one  stereopticon,  twelve  feet  by 
eight  feet. 

The  same  to  be  made  of  structural  steel  as  follows: 

Four  outside  horizontal  members  at  top  and  bottom. 

Four  corner  uprights  and  members  supporting  roof,  to  be 
made  of  one  and  one-half  inch  by  one  and  one-half  by  one- 
fourth  inch  angle-irons. 

Intermediate  uprights  to  be  spaced  every  two  feet,  and  to  be 
made  of  either  one  and  one-half  inch  by  one  and  one-half  inch 
by  one-fourth  inch  angle-irons  or  two  inch  by  two  inch  by  one- 
fourth  inch  tee-irons. 

Tee-irons,  to  which  roof  is  attached,  to  be  made  of  one  and 
one-half  inch  by  one  and  one-half  inch  by  three-sixteenth  inch 
tee-irons. 

All  joints  to  be  made  with  a  three-sixteenth  inch  steel  plate, 
to  which  each  angle-iron  or  tee-iron  shall  be  riveted  or  bolted 
by  the  use  of  at  least  (2)  one-fourth  inch  bolts  or  rivets. 

All  bolts  or  rivets  in  frame  to  have  flat  heads,  said  heads  al- 
ways to  be  placed  on  exterior  side  of  booth;  all  angle  or  tee- 
irons  being  so  countersunk  as  to  accomplish  this  result. 

Frame  to  be  built  with  a  six-foot  by  two-foot  doorway;  frame 
of  said  doorway  to  be.  built  of  one  inch  by  one  inch  by  three- 
sixteenth  inch  angle-irons,  which  are  to  be  joined  together  by 
the  use  of  a  three-sixteenth  inch  steel  plate. 

Covering  of  Booth:  Sides  and  top  of  booth  to  be  covered  with 
asbestos  boards  of  at  least  one-fourth  inch  in  thickness;  said 
boards  to  be  cut  and  arranged  that  vertical  joints  between 
boards  shall  always  come  over  an  angle  or  tee-iron,  so  that 
both  boards  may  be  securely  fastened  to  the  same. 


470  MOTION     PICTURE     PROJECTION 


After  booth  is  complete,  all  openings  where  combustible  ma- 
terial is  exposed  must  be  plugged  with  asbestos  cement,  or 
other  equally  satisfactory  material.  When  joints  of  asbestos 
boards,  on  outside  of  booth,  do  not  come  over  angles  of  tee- 
irons,  the  cracks  between  the  boards  shall  be  covered  by  a  strip 
of  asbestos  board  at  least  one-eighth  inch  thick  and  two  inches 
wide;  said  strips  to  be  securely  fastened  to  both  boards  in  such 
manner  as  to  cover  the  exposed  points.  The  above-mentioned 
strips  and  all  asbestos  boards  shall  be  secured  in  the  proper 
place  by  the  means  of  proper  bolts  and  nuts;  said  bolts  and 
nuts  to  be  spaced  not  more  than  six  inches  apart. 

Flooring:  Floor  shall  be  made  of  two  parts,  an  upper  and  a 
lower  floor.  Lower  floor  shall  be  made  of  boards  seven-eighth 
inch  minimum  thickness,  supported  on  lower  leg  of  horizontal 
angle-irons.  Resting  on  this  floor  shall  be  a  floor  made  of  as- 
bestos boards  of  three-eighth  inch  minimum  thickness,  or  an 
equally  good  material. 

Windows:  There  shall  not  be  more  than  two  windows  per 
machine  in  the  booth — one  for  the  operator  and  one  for  the 
machine.  Window  for  machine  shall  not  be  more  than  six 
inches  high  and  twelve  inches  long,  and  shall  be  located  and 
cut  after  machine  is  set  up.  Operator's  window  shall  not  be 
more  than  four  inches  wide  or  more  than  twelve  inches  high. 

All  windows  shall  be  provided  with  gravity-doors,  which, 
when  closed,  shall  overlap  the  window  opening  at  least  one  inch 
on  all  sides;  said  doors  to  be  held  open  normally  by  use  of  a 
fine  combustible  cord  in  series  with  a  fusible  link,  so  arranged 
that  the  doors  may  easily  be  released  by  hand. 

Main  Door:  Outside  of  door  to  be  provided  with  a  substan- 
tial spring,  sufficient  to  keep  door  closed.  Door  to  be  provided 
with  stop  to  prevent  it  from  swinging  into  booth  or  injuring 
the  hinges. 

Shelves:  To  be  made  up  of  slate  slabs  or  board  not  less 
than  seven-eighth  inch  thick,  not  exceeding  four  feet  in  length 
or  twelve  inches  in  width.  Said  shelves,  if  of  board,  to  be 
painted  with  at  least  three  coats  of  asbestos  paint,  and  sup- 
ported by  means  of  angle-iron.  Upper  shelf  to  be  used  for  the 
rewinding  and  the  repairing  of  films;  the  lower  shelf  to  be  used 
for  the  storage  of  films.  A  separate  metal  case,  made  without 
solder,  shall  be  provided  for  each  film  when  the  same  is  not  in 
the  magazine  or  in  the  process  of  winding;  said  films  to  be  kept 
in  these  cases. 

Ventilation:  Booths  to  be  provided  with  an  inlet  in  each  of 
four  sides;  said  inlets  to  be  fifteen  inches  long,  three  inches 
high,  the  lower  side  of  the  same  not  to  be  more  than  three 
inches  above  floor  level.  Said  inlets  to  be  covered  on  the  inside 


MOTION     PICTURE     PROJECTION  471 

by  a  wire  net  of  not  greater  than  one-eighth  inch  mesh  netting, 
to  be  firmly  secured  to  the  asbestos  boards  by  means  of  iron 
strips  and  screws. 

Near  the  center  at  the  top  of  the  booth  shall  be  a  circular 
opening  of  not  less  than  ten  inches  in  diameter ;  the  upper  side 
of  said  opening  to  be  provided  with  an  iron  flange;  which  flange 
is  to  be  securely  fastened  to  the  tee-irons  supporting  the  roof. 
Securely  fastened  to  this  flange  shall  be  a  vent-pipe  of  not  less 
than  ten  inches  in  diameter ;  said  pipe  leading  to  the  outside  of 
the  building  or  to  a  special  incombustible  vent-flue.  In  this 
vent-pipe  shall  be  placed  a  box  containing  a  twelve-inch  electric 
fan;  said  box  to  be  provided  with  a  door  of  sufficient  size  to 
permit  of  the  examination  or  removal  of  this  fan;  this  door  to 
be  made  tight,  and  provided  with  proper  fastenings.  Box  and 
vent-pipes  to  be  made  of  galvanized  iron  or  other  non-qom- 
bustible  material;  fan  to  be  so  connected  that  it  can  be  con- 
trolled from  within  the  booth. 

Wiring:  If  house  lights  are  controlled  from  within  the  booth, 
an  additional  emergency  control  must  be  provided  near  the 
main  exit  and  kept  at  all  times  in  good  condition. 

All  electric  wires  to  be  brought  in  to  the  booth  and  carried 
to  all  machines,  lights,  et  cetera,  in  conduits;  one  light  will  be 
allowed  for  each  machine,  and  one  for  the  rewinding-bench,  but 
all  such  lights  shall  be  provided  with  wire  guards. 

Rheostats:  All  rheostats  toi  be  mounted  on  slate  insulator, 
properly  supported;  said  supports  to  be  made  of  iron  and  se- 
curely fastened  to  the  floor;  rheostats  to  be  securely  fastened 
to  slate  insulator. 

Machine:  Must  be  securely  fastened  to  the  floor  to  prevent 
accidental  overturning  of  the  same:  Provided,  that  this  section 
shall  not  apply  to  cities  of  the  first  and  second  clases. 

Sect.  2.  That  it  shall  be  unlawful  for  any  person,  firm,  as- 
sociation, or  corporation  to  erect,  set  up,  construct,  maintain, 
or  use  any  portable  booth  or  enclosure,  for  the  purpose  of  oper- 
ating therein  moving-picture  machines,  unless  they  are  built, 
erected  and  constructed  as  follows: 

Size:  Portable  booths  or  enclosures  are  to  be  at  least  six 
and  one-half  feet  high  and  five  feet  square,  and  are  permitted 
for  the  use  of  one  picture  machine  only. 

Frame:  The  frame  is  to  be  made  of  standard  pipe  angle- 
iron,  ventilator  trap,  and  suitable  fittings.  The  pipe  frame  and 
angle-iron  trap  are  to  conform  strictly  to  specifications  here- 
inafter set  forth,  and  the  fittings  and  details  of  construction 
must  be  approved  by  the  Department  of  Factory  Inspection  of 
the  Commonwealth  of  Pennsylvania. 


472  MOTION     PICTURE     PROJECTION 


Skeleton  Frame:  Four  corner  uprights,  to  be  made  of  three- 
quarter  inch  standard  pipe. 

Eight  horizontal  members,  to  be  made  of  three-quarter  inch 
standard  pipe. 

Eight  corner  fittings,  to  be  made  of  iron  or  bronze  castings. 

Ventilator  Trap:  Ventilator  trap,  to  be  made  of  one-inch 
by  one-eighth  inch  angle-iron,  shall  extend  full  width  of  the  top 
and  two  inches  beyond  the  front  of  the  top  pipe;  shall  be  suit- 
ably hinged,  not  less  than  two  feet  from  the  edge  of  the  front 
angle  corners,  and  joints  to  be  made  with  one-eighth  inch  steel 
plates,  riveted  or  bolted  to  each  angle-iron  by  the  use  of  at 
least  two  three-sixteenths  inch  rivets  or  bolts. 

Covering  of  Booth:  The  side  and  top  covering  of  the  booth 
shall  be  made  of  an  approved  pure  asbestos  cloth,  same  as  used 
for  asbestos  curtains,  weighing  not  less  than  two  pounds  to  the 
square  yard.  Seams  and  hems  in  the  asbestos  cloth  shall  lap  at 
least  one  inch,  and  be  stitched  on  each  edge  with  asbestos  sew- 
ing twine.  The  top  covering  shall  be  made  separate  from  the 
side  covering.  It  shall  completely  cover  the  top  and  have  the 
outside  flap  hang  down  all  around  the  sides,  not  less  than  six 
inches  deep.  It  shall  be  fastened  tightly  and  secured  to  the  top 
pipes  and  ventilator  trap  by  means  of  asbestos  cords.  The  side 
covering  shall  be  made  in  one  piece,  extending  around  all  four 
sides,  and  overlapping  at  the  rear  of  the  booth  not  less  than 
eighteen  inches,  so  as  to  form  a  flap  doorway.  The  side  cover- 
ing shall  extend  from  top  pipes —  to  which  it  shall  be  suspended 
by  approved  metal  hooks  or  rings,  spaced  not  more  than  twelve 
inches  apart — to  the  floor,  with  a  flap  of  not  less  than  three 
inches  all  around  resting  on  the  floor.  The  metal  hooks  or  rings 
for  suspending  the  side  covering  shall  be  attached  to  the  hem 
of  the  cloth  by  means  of  a/  metal  strap  and  two  rivets.  The 
side  covering  shall  be  drawn  down  tight  and  secured  to  the  bot- 
tom pipe  frame  by  means  of  asbestos  tie  cord.  The  cloth  cover- 
ing for  top  and  sides  must  at  all  times  be  kept  free  from 
rents  or  holes  and  be  maintained  in  good  condition. 

The  side  covering  shall  overlap  eighteen  inches  in  the  rear  of 
the  booth.  This  overlap  shall  extend  from  top  to  bottom  and 
shall  be  so  arranged  as  to  form  a  means  of  entrance  and  egress. 

Flooring:  The  frame  shall  be  placed  on  a  mat  or  carpet 
made  of  approved  asbestos  cloth,  not  less  than  seven  feet 
square.  This  mat  must  be  spread  out  smoothly  on  a  substantial 
floor  or  platform,  so  that  it  shall  extend  one  foot  from  the 
frame  on  all  sides. 

Ventilation:  The  top  of  the  frame  shall  be  fitted  at  the  rear 
with  a  hinged  ventilator  trap,  as  described  in  foregoing  section 
of  frame.  The  asbestos  cloth  top  covering  shall  be  so  arranged, 


MOTION"     PICTURE     PROJECTION  473 


and  so  attached  to  the  frame  that,  when  the  hinged  trap  is 
raised,  the  asbestos  covering  shall  be  raised  also  in  the  rear. 

Windows:  The  look-out  window  for  the  operator  shall  be  not 
more  than  four  inches  wide  and  twelve  inches  high.  The  win- 
dows for  the  machine  shall  not  be  more  than  six  inches  high 
and  twelve  inches  long.  All  windows  shall  be  located  and  cut 
after  machine  is  set  up. 

The  openings  shall  be  cut  in  the  cloth  with  care  and  the  edges 
reinforced  by  stitched  hems  of  asbestos  cloth;  they  shall  be 
provided  with  asbestos  flaps,  securely  stitched  at  the  top  of  the 
openings.  These  flaps,  when  closed,  shall  overlap  the  window 
opening  at  least  two  inches  on  the  bottom  and  sides,  and  shall 
be  weighted  across  the  bottom  edge  by  a  piece  of  three-eighth 
inch  pipe,  or  equal  weight  of  metal,  securely  sewed  in  the 
pocket  in  the  cloth. 

Window  Shutters  and  Ventilator  Trap:  The  window  flaps 
or  shutters  are  to  be  held  open  normally  by  the  use  of  a  fine 
combustible  cord.  The  hinged  ventilator  trap  is  to  be  raised, 
for  ventilation,  not  more  than  six  inches  at  the  rear,  and  shall 
be  held  open  by  a  collapsible  prop  sustained  by  fine  combustible 
cord.  The  cord  from  the  window  shutters  and  the  ventilator 
prop  shall  be  in  series  with  a  fusible  link,  and  also  approved 
tension  clip,  so  arranged  that  the  automatic  opening  of  the  link, 
or  release  of  the  tension  clip  by  the  operator,  will  insure  the 
immediate  closing  of  all  openings  by  the  dropping  of  the  flaps 
and  the  ventilator  trap.  This  fusible  link  and  tension  clip  shall 
be  arranged  in  a  position  directly  over  the  machine,  within 
reach  of  the  operator. 

Provided,  hovever,  that  portable  booths  or  enclosures  shall  not 
be  permitted  to  be  used  in  any  theatre  or  public  hall  in  which 
permanent  booths  or  enclosures  have  been  installed;  it  being 
the  intention  of  this  section  that  portable  booths  or  enclosures 
shall  be  used  only  for  temporary  exhibitions  of  moving  pictures 
in  places  of  assemblage — such  as  schools,  churches,  association 
halls,  lodge  rooms,  theatres — without  permanent  booths.  Pro- 
vided, That  this  section  shall  not  apply  to  cities  of  the  first  and 
second  classes. 

Sect.  3.  It  shall  be  the  duty  of  the  Department  of  Factory 
Inspection,  by  and  through  its  Chief  Factory  Inspector,  his 
deputy  or  deputies,  to  take  such  means  as  it  may  deem  neces- 
sary to  enforce  the  provisions  of  this  statute.  It  shall  be  the 
duty  of  said  Chief  Factory  Inspector,  his  deputy  or  deputies, 
within  a  reasonable  time  after  the  approval  of  this  act,  to  in- 
spect all  booths  or  enclosures  in  which  moving  pictures  are  now 
being  operated.  Any  such  person  or  persons,  who  shall  fail  to 
comply  with  the  said  order  of  abatement  or  discontinuance,  so 


474  MOTION     PICTURE     PROJECTION 

issued  as  aforesaid,  shall  be  deemed  guilty  of  a  misdemeanor, 
and,  on  conviction,  shall  be  punished  by  a  fine  of  not  less  than 
twenty-five  dollars  and  not  more  than  five  hundred  dollars,  or 
an  imprisonment  in  the  county  jail  for  a  term  of  not  less  than 
ten  days  nor  more  than  ninety  days,  within  the  discretion  of  the 
court,  for  each  and  every  such  violation. 

Sect.  4.  Any  person  or  persons  who  violate  or  ignore  any  of 
the  provisions  of  sections  one  and  two  of  this  act  shall  be 
deemed  guilty  of  misdemeanor,  and  on  conviction  thereof  shall 
be  punished  by  a  fine  of  not  less  than  fifty  dollars  and  not 
more  than  five  hundred  dollars,  or  an  imprisonment  in  the 
county  jail  for  a  term  of  not  less  than  ten  days  nor  more  than 
ninety  days,  for  each  and  every  violation. 

Laws  1909;  No.  206;  page  346. 
Laws  1911;  page  64. 

§  1.  That  it  shall  be  unlawful  for  any  person  or  persons  to 
give  or  participate  in,  or  for  the  owner  or  owners  of  any  build- 
ing, tent,  tents,  or  any  premises,  lot,  park,  or  common  or  anyone 
having  control  thereof  to  permit  within  said  building,  tent  or 
tents,  or  any  premises,  lot,  park  or  common,  the  exhibition  of 
any  fixed  or  moving  pictures  of  a  lascivious,  sacrilegious,  ob- 
scene, indecent,  or  of  an  immoral  nature  and  character  or  such 
as  might  tend  to  corrupt  morals. 

§  2.  Any  person  who  shall  violate  any  of  the  provisions  of 
the  1st  section  of  this  act  shall  be  deemed  guilty  of  misdemeanor 
and  upon  conviction  thereof  shall  be  sentenced  to  pay  a  fine 
not  exceeding  $1,000  or  suffer  an  imprisonment  in  the  jail  of  the 
proper  county  for  a  period  not  exceeding  one  year,  or  either 
or  both,  within  the  discretion  of  the  court. 

Laws  1911;  page  746. 

To  regulate  the  construction,  maintenance  and  inspection  of 
buildings  used  for  the  exhibition  of  moving  pictures  in  all  cities 
of  the  first  class. 

Laws  1913;  No.  229. 

§  4  (on  page  230).  The  annual  license  fee  for  any  places  of 
amusement,  buildings,  tents  or  inclosures,  or  any  part  thereof 
situated  in  any  city,  borough  or  township  of  this  commonwealth, 
which  is  used  for  the  exhibition  of  fixed  or  moving  pictures  or 
stereoptican  views  exclusively  (whether  scenery  or  apparatus 
are  employed  or  not)  shall  be  $25,  irrespective  of  the  number 
of  chairs  or  seating  capacity  of  such  places  of  amusement, 
buildings,  tents  or  inclosures.  (State  Board  of  Censors.) 


MOTION     PICTURE     PROJECTION  475 

Laws  1915;  No.  239. 

§  2.  It  shall  be  unlawful  to  sell,  lease,  lend,  exhibit  or  use 
any  motion  picture  film,  reel  or  view,  in  Pennsylvania,  unless 
the  said  film,  reel  or  view  has  been  submitted  by  the  exchange, 
owner,  or  lessee  of  the  film,  reel  or  view,  and  duly  approved  by 
the  Pennsylvania  State  Board  of  Censors. 

§  7.  Upon  each  film,  reel  or  view  which  has  been  approved 
by  the  board,  there  shall  be  furnished  and  stamped  by  the  board 
the  following  certificate  or  statement:  Approved  by  Pennsyl- 
vania State  Board  of  Censors;  and  shall  also  furnish  a  certifi- 
cate in  writing  to  the  same  effect,  which  certificate  shall  be 
exhibited  to  any  member  of  the  board  of  employee  thereof  upon 
demand  of  the  holder  thereof. 

In  the  case  of  motion  pictures,  shall  be  shown  on  the  screen 
to  the  extent  of  approximately  4  feet  of  film. 

In  case  of  slides  or  views,  each  set  shall  have  at  least  two 
slides  or  views  shown  with  a  similar  statement. 

§  17.  For  the  examination  of  each  film,  reel  or  set  of  views 
of  1200  linear  feet  or  less  the  board  shall  receive  in  advance  a 
fee  of  $1  and  $1  for  each  duplicate  or  print  thereof  which  must 
be  applied  for  at  the  same  time  and  by  the  same  person. 

§  20.  Any  member  or  employee  of  the  board  may  enter  any 
place  where  films,  reels  or  views  are  exhibited;  and  such  mem- 
ber or  employee  is  hereby  empowered  and  authorized  to  pre- 
vent the  display  or  exhibition  of  any  film,  reel  or  view  which  has 
not  been  duly  approved  by  the  board. 

§  24.  Every  person  intending  to  sell,  lease,  exhibit,  or  use 
any  film,  reel  or  view  in  Pennsylvania  shall  furnish  the  board 
when  the  application  for  approval  is  made,  a  description  of  the 
film,  reel  or  view,  to  be  exhibited,  sold  or  leased,  and  the  pur- 
poses thereof,  and  shall  submit  the  film,  reel  or  view  to  the 
board  for  examination;  and  shall  also  furnish  a  statement  or 
affidavit  that  the  duplicate  film,  reel  or  view  is  an  exact  copy  of 
the  original  film,  reel  or  view,  as  submitted  for  examination  to 
the  board  and  that  all  eliminations,  changes  or  rejections,  made 
or  required  by  the  board  in  the  original  film,  reel  or  view  has 
been  or  will  be  made  in  the  duplicate. 

§  25.  It  shall  be  unlawful  for  any  person  to  hinder  or  inter- 
fere in  any  manner  with  any  member  or  employee  of  the  board 
while  performing  any  duties  in  carrying  out  the  intent  or  pro- 
visions of  this  act. 

§  26.  If  any  elimination  or  disapproval  of  a  film,  reel  or 
view  is  ordered  by  the  board,  the  person  submitting  such  film, 
reel  or  view  for  examination  will  receive  immediate  notice  of 
such  elimination  or  disapproval,  and,  if  appealed  from,  such 
film,  reel  or  view  will  be  promptly  re-examined,  in  the  presence 


476  MOTION     PICTURE     PROJECTION 


of  such  person,  by  two  or  more  members  of  the  board  and  the 
same  finally  approved  or  disapproved  promptly  after  such  re- 
examination,  with  the  right  of  appeal  from  the  decision  of  the 
board  to  the  Court  of  Common  Pleas  of  the  proper  county. 

§  27.  Any  person  who  violates  any  of  the  provisions  of  this 
act  and  is  convicted  thereof  summarily  before  any  alderman, 
magistrate  or  justice  of  the  peace,  shall  be  sentenced  to  pay  a 
fine  of  not  less  than  $20  nor  more  than  $50  for  the  first  offense. 
For  any  subsequent  offense  the  fine  shall  not  be  less  than  $50 
nor  more  than  $100.  In  default  of  payment  of  a  fine  and  costs, 
the  defendant  shall  be  sentenced  to  imprisonment,  in  the  prison 
of  the  county  where  such  offense  was  committed,  for  not  less 
than  10  days  and  not  more  than  30  days. 

§  28.  If  any  person  shall  fail  to  display  or  exhibit  on  the 
screen  the  approval  seal  as  issued  by  the  board  of  a  film,  reel 
or  view  which  has  been  approved  and  is  convicted  summarily 
before  any  alderman,  magistrate  or  justice  of  the  peace,  he 
shall  be  sentenced  to  pay  a  fine  of  not  less  than  $5  and  not 
more  than  $10;  in  defaut  of  payment  of  a  fine  and  costs,  the 
defendant  shall  be  sentenced  to  imprisonment  in  the  prison  of 
the  county  where  such  offense  was  committed  for  not  less  than 
two  days  and  not  more  than  five  days. 


MOTION     PICTURE     PROJECTION  477 


NEW  YORK 

Penal  Law. 
Con.  Law;  Ch.  40. 

§  484;  Sub.  1. — Any  person  who  admits  to  or  allows  to  re- 
main in  any  kinetoscope  or  moving  picture  performance  owned, 
leased,  managed  or  controlled  by  him  or  by  his  employer,  or 
where  such  person  is  employed  or  performs  such  service  as  door 
keeper  or  ticket  seller  or  ticket  collector,  any  child  actually  or 
apparently  under  the  age  of  sixteen  years,  unless  accompanied 
by  its  parent  or  guardian,  or  unless  such  kinetoscope  or  moving 
picture  exhibition  is  given  under  the  auspices  or  for  the  benefit 
of  any  school  or  church  or  educational  or  religious  institution 
not  operated  for  profit,  is  guilty  of  a  misdemeanor. 

Penal  Law. 
Con.  Law;  Ch.  40. 

§  485.  Certain  employment  of  children  under  the  age  of  six- 
teen years  prohibited. 

Sub.  5  (as  amended  by  Law  1916;  Ch.  278). 

But  this  section  does  not  apply  to  the  employment  of  any 
child  in  posing  or  acting,  or  as  a  subject  for  use,  in  or  for,  or 
in  connection  with,  the  making  of  a  motion  picture  film  with 
the  written  consent  of  the  mayor  of  the  city,  or  the  president 
of  the  board  of  trustees  of  the  village  where  such  concert  or 
exhibition  takes  place.  Such  consent  shall  not  be  given  unless 
48  hours  previous  notice  of  the  application  shall  have  been 
served  in  writing  upon  the  society  mentioned  in  section  491  of 
this  chapter  (Society  for  the  Prevention  of  Cruelty  to  Chil- 
dren), if  there  be  one  within  the  county,  and  a  hearing  had 
thereon  if  requested  and  shall  be  revocable  at  the  will  of  the 
authority  giving  it.  It  shall  specify  the  name  of  the  child,  its 
age,  the  names  and  residence  of  its  parents  or  guardians,  the 
nature,  time,  duration  and  number  of  performances  permitted, 
together  with  the  place  and  character  of  the  exhibition;  and 
where  any  child  is  to  be  employed  in  the  making  of  a  motion 
picture  film  it  shall  provide  that  the  child  is  to  be  employed 
only  in  the  manner  described  and  set  forth  in  the  statement  in 
writing  submitted  with  the  application  as  hereinafter  provided. 
Any  person  applying  for  such  consent  for  the  use  or  employ- 
ment of  any  such  child  or  children  in  any  place  in  the  state, 
in  posing  or  acting  for  or  as  a  subject  for  use  in  or  in  con- 
nection with  the  making  of  a  motion  picture  film  shall  submit 


478  MOTION     PICTURE     PROJECTION 


with  such  application  a  true  and  accurate  statement  in  writing 
setting  forth  and  describing  in  detail  the  entire  part  to  be 
taken  and  each  and  every  act  and  thing  to  be  done  and  per- 
formed by  such  child  in  the  making  of  such  film,  to  the  local 
official  having  authority  to  issue  such  permits  or  of  any  such 
society  having  jurisdiction  in  such  place.  But  no  such  consent 
shall  be  deemed  to  authorize  any  violation  of  the  first,  second, 
fourth  or  fifth  subdivision  of  this  section. 

Laws  1918;  Ch.  308. 

(Being  Con.  Laws,  Ch.  20,  Article  12a.)     Gen.  Bus.  Law. 

§  209.  No  cinematograph  or  any  other  apparatus  for  pro- 
jecting moving  pictures  save  as  excepted  in  §§  211  and  213  of 
this  article  which  apparatus  uses  combustible  films  of  more 
than  10  inches  in  length,  shall  be  set  up  for  use  or  used  in  any 
building,  place  of  public  assemblage,  for  entertainment,  unless 
such  apparatus  for  the  projecting  of  moving  picture  shall  be 
inclosed  therein  in  a  booth  or  enclosure  constructed  of  concrete, 
brick,  hollow  tile  or1  other  approved  fireproof  framework  cov- 
ered or  lined  with  asbestos  board  or  with  some  other  approved 
fire  resisting  material,  and  unless  such  booth  shall  have  been 
constructed  as  provided  in  §  210  of  this  article  and  the  certifi- 
cate provided  in  §  212  of  this  article  shall  have  been  issued  to 
the  owner  or  lessee  of  the  premises  wherein  such  booth  is 
situated. 

§  210.  The  booth  provided  for  in  §  209  of  this  article  shall 
be  constructed  according  to  plans  and  specifications  which 
shall  have  been  first  approved,  in  a  city,  by  the  mayor  or  chief 
executive  officer  of  the  city  department  having  supervision  of 
the  erection  of  buildings  in  such  city ;  in  a  village,  by  the  presi- 
dent of  such  village;  in  a  town  outside  the  boundaries  of  a  city 
or  village,  by  the  supervisor  of  such  town.  Provided,  however, 
that  no  plans  and  specifications  for  the  construction  of  such 
booths  shall  be  approved  by  any  public  official,  unless  the  fol- 
lowing requirements  are  substantially  provided  for  in  such 
plans  and  specifications. 

1.  Dimensions. — Such  booths  shall  be  at  least  6  feet  in  height. 
If  one  machine  is  to  be  operated  in  such  booth  the  floor  space 
shall  be  not  less  than  48  square  feet.    If  more  than  one  machine 
it  to  be  operated  therein,  an  additional  24  square  feet  shall  be 
provided  for  each  additional  machilne. 

2.  General   Specifications. — In   case   such   booth   is  not  con- 
structed of  concrete,  brick,  hollow  tile  or  other  approved  fire 
proof  material  than  asbestos,  such  booth  shall  be  constructed 
with  an  angle  framework  of  approved  fireproof  material,  the 
angles  to  be  not  less  than  1%  inches  by  8/16  of  an  inch  thick, 


MOTION     PICTURE     PROJECTION  479 


the  adjacent  members  being  joined  firmly  with  angle  plates  of 
metal.  The  angle  members  of  the  framework  shall  be  spaced 
not  more  than  4  feet  apart  on  the  sides  and  not  more  than  3 
feet  apart  on  the  front  and  back  and  top  of  such  booth.  The 
sheets  of  asbestos  board  or  other  approved  fire  resisting 
material  shall  be  at  least  14  of  an  inch  in  thickness  and  shall  be 
securely  attached  to  the  framework  by  means  of  metal  bolts 
and  rivets.  The  fire  resisting  material  shall  completely  cover 
the  sides,  top  and  all  joints  of  such  booth.  The  floor  space 
occupied  by  the  booth  shall  be  covered  with  fire  resisting  ma- 
terial not  less  than  %  of  an  inch  in  thickness.  The  booth  shall 
be  insulated  so  that  it  will  not  conduct  electricity  to  any  other 
portion  of  the  building.  There  shall  be  provided  for  the  booth 
a  door  not  less  than  2  feet  wide  and  5  feet  10  inches  high,  con- 
sisting of  an  angle  frame  of  approved  fireproof  material  cov- 
ered with  sheets  of  approved  fireproof  material  V4  °f  an  mcn 
thick  and  attached  to  the  framework  of  the  booth  by  hinges,  in 
such  manner  that  the  door  shall  be  kept  closed  at  all  times, 
when  not  used  for  ingress  or  egress.. 

The  operating  windows,  one  for  each  machine  to  be  operated 
therein  and  one  for  the  operator  thereof,  shall  be  no  larger  than 
reasonably  necessary  to  secure  the  desired  service,  and  shutters 
of  approved  fireproof  material  shall  be  provided  for  each  win- 
dow. When  the  windows  are  open,  the  shutters  shall  be  so  sus- 
pended and  arranged  that  they  will  automatically  close  the 
window  openings,  upon  the  operating  of  some  suitable  fusible 
or  mechanical  releasing  device. 

Where  a  booth  is  so  built  that  it  may  be  constructed  to  open 
directly  on  the  outside  of  the  building  through  a  window,  such 
window  shall  be  permitted  for  the  comfort  of  the  operator,  but 
such  booth  shall  not  be  exempted  from  the  requirement  of  the 
installation  of  a  vent  flue  as  hereinafter  prescribed.  Said  booth 
shall  contain  an  approved  fireproof  box  for  the  storage  of  films 
not  on  the  projecting  machine.  Films  shall  not  be  stored  in  any 
other  place  on  the  premises;  they  shall  be  rewound  and 
repaired  either  in  the  booth  or  in  some  other  fireproof  enclo- 
sure. The  booth  in  which  the  picture  machine  is  operated  shall 
be  provided  with  an  opening  or  vent  flue  in  its  roof  or  upper 
part  of  its  side  wall  leading  to  the  outdoor  air.  The  vent  flue 
shall  have  a  minimum  cross-sectional  area  of  50  square  inches 
and  shall  be  fireproof.  When  the  booth  is  in  use  there  shall  be 
a  constant  current' of  air  passing  outward  through  said  opening 
or  vent  flue  at  the  rate  of  not  less  than  30  cubic  feet  per 
minute. 

§  211.  Sections  209  and  210  of  this  article  shall  not  be  retro- 
active for  any  booth  approved  by  the  appropriate  public  author- 


480  MOTION     PICTURE     PROJECTION 


ity  or  official  prior  to  this  article  taking  effect,  provided  such 
booth  have  or  be  so  reconstructed  of  the  same  material  as  to 
have  dimensions  as  specified  in  section  210  of  this  article;  pro- 
vided such  booth  conform  to  the  specifications  of  section  210  as 
regards  vent  flue,  box  for  storage  of  films,  specifications  for  re- 
winding and  repairing  films  and  specifications  for  windows  and 
doors,  and  provided  such  booth  be  of  rigid  fireproof  material, 
and  be  insulated  so  as  not  to  conduct  electricity  to  any  other 
part  of  the  building  and  be  so  separated  from  any  adjacent 
combustible  material  as  not  to  communicate  fire  through  intense 
heat  in  case  of  combustion  within  the  booth. 

§  212.  After  the  construction  of  such  booth  shall  have  been 
completed,  the  public  officer  charged  herein  with  the  duty  of 
passing  upon  the  plans  and  specifications  therefor  shall  within 
3  days  after  receipt  of  notice  in  writing  that  such  booth  has 
been  completed  cause  such  booth  to  be  inspected.  If  the  pro- 
visions of  sections  209  and  210  of  this  article  have  been  complied 
with,  such  public  officer  shall  issue  to  the  owner  or  lessee  of  the 
premises  wherein  such  booth  is  situated  a  certificate  stating  that 
the  provisions  of  sections  209  and  210  of  this  article  have  been 
complied  with. 

§  213.  Where  motion  pictures  are  exhibited  daily  for  not 
more  than  one  month,  or  not  oftener  than  3  times  a  week,  in 
educational  or  religious  institutions,  or  bona  fide  social,  scien- 
tific, political  or  athletic  clubs,  a  portable  booth  may  be  sub- 
stituted for  the  booth  required  in  sections  209  and  210  of  this 
article.  Such  booth  shall  have  a  height  of  not  less  than  6  feet 
and  an  area  of  not  less  than  20  square  feet  and  shall  be  con- 
structed of  asbestos  board,  sheet  steel  of  no  less  gauge  than 
24,  or  some  other  approved  fireproof  material.  Such  portable 
booth  shall  conform  to  the  specifications  of  section  210  of  this 
article  with  reference  to  windows  and  door,  but  not  with 
reference  to  vent  flues.  The  floor  of  such  booth  shall  be 
elevated  above  the  permanent  support  on  which  it  is  placed 
by  a  space  of  at  least  %  inch,  sufficient  to  allow  the  passage 
of  air  between  the  floor  of  the  booth  and  the  platform  on 
which  the  booth  rests,  and  the  booth  shall  be  insulated  so 
that  it  will  not  conduct  electricity  to  any  other  portion  of  the 
building. 

§  214.  (As  amended  by  Laws  1916;  Ch.  185). 

The  above  sections  209,  210,  211,  212  and  213,  referring  to 
permanent  and  portable  booths,  shall  not  apply  (a)  to  any 
miniature  motion  picture  machine  in  which  the  maximum  elec- 
tric current  used  for  the  light  shall  be  350  watts.  Such  minia- 
ture machine  shall  be  operated  in  an  approved  box  of  fireproof 
material  constructed  with  a  fusible  link  or  other  approved  re- 


MOTION     PICTURE     PROJECTION  481 


leasing  device  to  close  instantaneously  and  completely  in  case 
of  combustion  within  the  box.  The  light  in  said  miniature  ma- 
chine shall  be  completely  enclosed  in  a  metal  lantern  box 
covered  witn  an  unremovable  roof,  (b)  To  the  use  or  operation 
of  any  so-called  miniature  motion  picture  apparatus  which  uses 
only  an  enclosed  incandescent  electric  lamp  and  approved  ace- 
tate of  cellulose  or  slow  burning  films,  and  is  of  such  construc- 
tion that  films  ordinarily  used  on  full-sized  commercial  picture 
apparatus  cannot  be  used  therewith. 

§  215.  Before  moving  pictures  shall  be  exhibited  with  a  port- 
able booth  under  section  213  of  this  article,  and  before  a  minia- 
ture machine  without  a  booth  shall  be  used  as  prescribed  in 
section  214  of  this  article,  there  shall  be  obtained  from  the 
appropriate  authority,  as  defined  in  section  210  of  this  article, 
a  certificate  of  approval. 

§  216.  The  violation  of  any  of  the  provisions  of  this  article 
shall  constitute  a  misdemeanor.  This  act  shall  not  apply  to 
cities  which  have  local  laws  or  ordinances  now  in  force  which 
provide  for  fireproof  booths  of  any  kind  for  moving  picture 
machines  or  apparatus. 

Laws  1916;  Ch.  184. 

(Being  Con.  Laws,  Ch.  21,  §  18  and  §  18a.  Gen.  City  Law.) 
§  18.  It  shall  not  be  lawful  for  any  person  or  persons,  save 
as  excepted  in  section  18a  of  this  article,  to  operate  any  moving 
picture  apparatus  and  its  connections  in  a  city  of  "the  first 
class  unless  such  person  or  persons  so  operating  such  apparatus 
is  duly  licensed  as  hereinafter  provided.  Any  person  desiring 
to  act  as  such  operator  shall  n.ake  application  for  a  license 
to  so  act  to  the  mayor  or  licensing  authority,  designated  by  the 
mayor,  unless  the  charter  of  said  city  so  designates,  which 
officer  shall  furnish  to  each  applicant  blank  forms  of  applica1- 
tion  which  the  applicant  shall  fill  out.  Such  officer  shall  make 
rules  and  regulations  governing  the  examination  of  applicants 
and  the  issuance  of  licenses  and  certificates.  The  applicant 
shall  be  given  a  practical  examination  under  the  direction  of 
the  officer  required  to  issue  such  license  and  if  found  competent 
as  to  his  ability  to  operate  moving  picture  apparatus  and  its 
connections  shall  receive  within  6  days  after  such  examination 
a  license  as  herein  provided.  Such  license  may  be  revoked  or 
suspended  at  any  time  by  the  officer  issuing  the  same.  Every 
license  shall  continue  in  force  for  one  year  from  the  date 
of  issue  unless  sooner  revoked  or  suspended.  Every  licence 
unless  revoked  or  suspended,  as  herein  provided,  may  at  the 
end  of  one  year  from  the  date  of  issue  thereof  be  renewed 
by  the  officer  issuing  it  in  his  discretion  upon  application  and 


482  MOTION     PICTURE     PROJECTION 


with  or  without  further  examination  as  he  may  direct.  Every 
application  for  renewal  of  license  must  be  made  within  the  30 
days  previous  to  the  expiration  of  such  license.  With  every 
license  granted  there  shall  be  issued  to  every  person  obtaining; 
such  license  a  certificate,  certifying  that  the  person  named 
therein  is  duly  authorized  to  operate  moving  picture  apparatus 
and  its  connections.  Such  certificate  shall  be  displayed  in  a 
conspicuous  place  in  the  room  where  the  person  to  whom  it  is 
issued  operates  moving  picture  apparatus  and  its  connections. 
No  person  shall  be  eligible  to  procure  a  license  unless  he  shall 
be  of  full  age.  Any  person  offending  against  the  provisions  of 
this  section,  asl  well  as  any  person  who  employs  or  permits  a 
person  not  licensed  as  herein  provided  to  operate  moving  pic- 
ture apparatus  and  its  connections,  shall  be  guilty  of  a  misde- 
meanor and  upon  conviction  thereof  shall  be  punished  by  a  fine 
not  exceeding  the  sum  of  $100,  or  imprisonment  for  a  period 
not  exceeding  3  months,  or  both. 

§  18a.  Nothing  contained  in  §  18  shall  be  considered  to  apply 
to  any  so-called  miniature  motion  picture  apparatus  which  uses 
only  an  enclosed  incandescent  electric  lamp  and  approved 
acetate  of  cellulose  or  slow  burning  films,  and  is  of  such  con- 
struction that  films  ordinarily  used  on  full  sized  commercial 
picture  apparatus  cannot  be  used  therewith. 

Laws  1916;  Ch.' 622. 

(Being  an  amendment  to  Workmen's  Compensation  Law. 
Con.  Law,  Ch.  67,  §  2,  group  40.) 

§  2.  Compensation  provided  for  in  this  chapter  shall  be  pay- 
able for  injuries  sustained  or  death  incurred  by  employees  en- 
gaged in  the  following  hazardous  employments: 

Group  40. — Manufacture  of  moving  picture  machines  and 
films. 


MOTION     PICTURE     PROJECTION  483 


NEW    JERSEY 

All  lights  used  in  theatres  shall  be  properly  protected  by 
globes  or  glass  coverings,  or  in  such  other  manner  as  the  board 
or  body  having  control  of  the  extinguishment  of  fires  in  any 
such  city  shall  prescribe;  the  owners  or  managers  or  the  per- 
sons having  charge  thereof,  shall  provide,  such  means  of  com- 
municating alarms  of  fire,  accident  or  danger  to  the  police  and 
fire  departments  respectively,  and  shall  also  provide  such  fire 
hose,  fire  extinguishers,  buckets,  fire  hooks,  axes,  fire  doors  and 
other  means  of  preventing  and  extinguishing  fires  as  the  body 
or  board  having  control  of  the  extinguishment  of  fire  shall 
direct;  no  obstruction  or  any  article  or  thing  whatever  shall  be 
placed  in  any  aisle  or  passageway  in  any  such  theatre. 

The  board  or  body  having  control  of  the  extinguishment  of 
fires  may  detail  not  to  exceed  two  members  of  its  force  at  each 
and  every  place  of  public  amusement  where  machinery  and 
scenery  are  used  while  such  place  is  open  to  the  public,  whose 
duty  it  shall  be  to  guard  against  fire,  and  who  shall  have  charge 
and  control  of  the  means  provided  for  its  extinguishment  and 
shall  have  the  direction  and  control  of  the  employees  of  the 
place  to  which  they  may  be  detailed,  for  the  purpose  of  extin- 
guishment of  any  fire  which  may  occur  therein. 

Any  person  or  corporation  who  shall  wilfully  violate,  or 
neglect  or  refuse  to  comply  with  any  provision  or  requirements 
of  this  act,  on  any  regulation,  order  or  special  direction  duly 
made  thereunder,  shall  for  every  such  offense,  pay  to  the  city 
in  which  such  offense  shall  be  committed,  a  penalty  of  not  less 
than  fifty,  nor  more  than  two  hundred  dollars  in  the  direction 
of  the  judge  or  court,  which  penalty  may  be  recovered  in  any 
court  now  or  hereafter  provided  for  the  enforcement  of  the  ordi- 
nance of  such  city,  and  for  the  collection  of  penalties  for  the 
violation  thereof,  and  it  shall  be  the  duty  of  the  board  or  body 
having  the  control  of  the  extinguishment  of  fires  in  such  city  to 
enforce  the  provisions  of  this  act,  and  to  arrest  any  person  or 
persons  who  shall  violate  the  provisions  of  this  act,  or  any  regu- 
lation, order  or  special  direction  duly  made  thereunder. 

Laws  1912;  Ch.  197. 

§  1.  It  shall  be  unlawful  tb  use  or  to  set  for  use  any  cine- 
matograph or  other  apparatus  or  machine  for  projecting  or 
exhibiting  moving  pictures,  when  such  apparatus  or  machine 
uses  films  of  a  combustible  material  more  than  ten  inches  in 
length,  in  any  building,  place  of  public  assemblage  or  entertain- 
ment, unless  such  apparatus  or  machine  be  enclosed  in  a  booth 


484  MOTION     PICTURE     PROJECTION 


or  other  enclosure  covered  or  lined  with  asbestos  or  other  strong 
and  fire-resisting  material  that  will  withstand,  on  a  twelve  inch 
square  sample  at  least  a  centre  load  of  at  least  250  pounds,  and 
which  shall  be  sufficient  to  resist  a  temperature  of  at  least  1500 
degrees  Fahrenheit  for  at  least  thirty  mniutes,  and  after  which 
being  immersed  in  water,  will  not  lose  more  than  fifty  per 
centum  of  its  initial  strength. 

§  2.  The  booths  provided  for  in  the  last  section  of  this  act 
shall  be  at  least  seven  feet  in  height,  inside  dimensions;  if  for 
the  use  of  one  such  machine  or  apparatus  as  is  mentioned  in  the 
last  section,  the  area  occupied  by  such  booth  shall  not  be  less 
than  48  square  feet ;  if  more  than  one  such  machine  or  apparatus 
is  to  be  operated  therein,  an  additional  24  square  feet  of  area 
shall  be  provided.  Such  booth  shall  be  constructed  with  a 
framework  of  iron  angles  not  less  than  1%  inches  by  1%  inches 
by  3/16  of  an  inch  thick.  The  adjacent  iron  members  being 
firmly  joined  with  angle  plates  or  iron;  the  iron  members  of 
the  framework  shall  be  spaced  not  more  than  4  feet  apart.  The 
fire  material  herein  mentioned  shall  completely  cover  the  sides 
and  top ;  all  joints  of  such  booth  and  framework  shall  be  pointed 
up  with  asbestos  retort  cement ;  the  sheets  of  such  fire  resisting 
material  shall  be  at  least  %  of  an  inch  in  thickness,  and  shall  be 
securely  attached  to  the  iron  framework  by  means  of  iron  bolts 
and  rivets.  The  floor  of  such  booth  shall  be  covered  with  such 
fire  resisting  material  not  less  than  %  of  an  inch  in  thickness. 
For  each  booth  there  shall  be  provided  a  door  not  less  than  two 
feet  in  width  and  six  feet  in  height,  consisting  of  an  angle  iron 
frame  covered  with  sheets  of  said  fire  resisting  material  %  of 
an  inch  in  thickness,  and  attached  to  the  framework  of  such 
booth  by  hinges,  in  such  manner  that  the  door  shall  be  kept 
closed  automatically  at  all  times,  when  not  used  for  ingress  or 
egress.  The  windows  in  such  booth  used  in  connection  with  the 
machines  and  apparatus,  and  by  the  operators  thereof,  shall 
not  be  larger  than  is  reasonably  necessary  to  secure  the  desired 
service,  and  such  fire  resisting  material  shall  be  provided  for 
each  window  and  shall  be  so  suspended  and  arranged  that  they 
will  automatically  close  the  window  openings  upon  the  operation 
of  either  a  fusible  or  mechanical  releasing  device,  with  a  fusible 
link  attached,  also  booth  to  be  provided  with  an  opening  for 
ventilation,  this  opening  to  be  provided  with  an  automatically 
closing  door  or  a  riveted  conductor  pipe  to  outside  of  building 
or  into  chimney. 

§  3.  No  booth  of  the  character  above  mentioned  shall  be 
constructed  until  plans  and  specifications  therefor  have  been 
submitted  to  and  approved  by  the  executive  officer  of  the 
municipality  wherein  such  booth  is  to  be  constructed,  having  in 


MOTION     PICTURE     PROJECTION  485 


charge  the  department  relating  to  the  erection  of  buildings,  or 
in  municipalities  where  no  such  department  exists  by  the  execu- 
tive officer  or  body  in  charge  of  the  fire  department  thereof;  no 
plans  or  specifications  shall  be  approved  which  do  not  conform 
to  the  minimum  requirements  set  forth  in  the  last  preceding 
section  hereof. 

§  4.  Every  such  certificate  of  approval  shall  expire  in  60 
days  after  its  date,  and  no  booth  shall  be  erected  under  such 
certificate  of  approval  unless  the  same  be  erected  within  60 
days  from  the  date  of  such  approval. 

§  5.  After  any  booth  shall  have  been  constructed  in  accord- 
ance with  the  terms  of  this  act,  the  owner  of  the  premises 
wherein  the  same  is  to  be  located,  or  the  lessee  thereof,  or  the 
person  for  whom  such  booth  is  being  constructed,  shall  notify 
the  proper  officer  or  body  provided  in  this  act,  of  the  fact  of 
the  completion  of  such  construction,  within  five  days  after  such 
completion.  Thereupon  such  officer  or  body  shall  cause  such 
booth  to  be  inspected,  and  if  found  to  have  been  constructed  in 
accordance  with  the  plans  and  specifications,  and  with  the  re- 
quirements of  this  act,  and  in  such  manner  as  to  render  safe 
the  operation  of  the  apparatus  or  machines  intended  to  be  used 
therein  for  the  purpose  of  projecting  moving  pictures,  such 
officer  or  body  shall  issue  to  the  owner,  lessee  or  other  person 
above  mentioned,  a  certificate  to  that  effect.  Such  certificate 
shall  be  posted  in  such  public  part  of  such  booth  as  to  enable 
the  same  to  be  distinctly  seen  from  a  point  in  such  building  or 
place  of  assemblage  at  least  five  feet  distant  from  such  booth. 

§  6.  The  board  or  body  having  charge  of  the  supervision 
and  control  of  the  erection  of  buildings  in  any  municipality  shall 
prescribe  the  details  for  the  submission  of  plans  and  specifica- 
tions and  their  approval,  the  inspection  of  such  booth  and  their 
approval  and  the  issuance  of  certificates  under  this  act,  and 
shall  fix  the  fees  to  be  paid  for  such  certificates  and  inspection. 

§  7.  For  a  violation  of  any  of  the  provisions  of  this  act  the 
person  so  offending  shall  be  fined  the  sum  of  $50;  on  complaint 
and  proof  of  such  violation  before  any  police  justice,  recorder, 
justice  of  the  peace  or  other  magistrate  in  municipalities  where 
the  office  of  police  justice  or  recorder  does  not  exist;  and  such 
penalty  shall  be  inflicted  for  each  day,  such  violation  may  be 
persisted  in.  Such  penalty  may  be  exacted  against  the  owner 
or  lessee  of  the  premises  wherein  such  violation  occurs,  or  both. 

§  8.  This  act  shall  take  effect  immediately  and  all  acts  and 
parts  of  acts  inconsistent  with  the  provisions  hereof  are  hereby 
repealed. 


486  MOTION     PICTURE     PROJECTION 

Laws  1914;  Ch.  190. 

(Being  a  Supplement  to  Laws  1912;  Ch.  197.) 
§  1.  The  act  to  which  this  act  is  a  supplement  shall  not 
apply  to  moving  picture  machines  using  only  cellulose  acetate 
films  not  more  than  100  feet  in  length  nor  more  than  one  inch 
in  width  and  not  requiring  more  than  500  watts  of  electric 
current  to  operate  the  arc,  except  when  such  machines  are  used 
or  exhibited  in  theatres  or  public  places  of  entertainment,  regu- 
larly used  as  such,  to  which  admission  fees  are  charged. 

Laws  1913;  Ch.  122. 
(Being  a  Supplement  of  the  "City  Commission  Act"  Law  of 

1911;  Ch.  221.) 

§  1.  In  order  to  lessen  the  dangers  caused  by  fire,  explosion 
and  panic,  the  board  of  commissioners  shall  have  power  to  regu- 
late the  use  of  dance  halls,  schools,  churches,  opera  houses,  and 
all  buildings  used  for  public  entertainment  or  amusement;  to 
compel  the  owners,  lessees,  or  person  operating  or  controlling 
the  same  to  provide  adequate  and  sufficient  exits  and  fire  es- 
capes therefrom,  and  to  prevent  the  obstruction  thereof;  to 
properly  guard  all  lights  and  electric  wires  therein ;  to  regulate 
the  construction,  installation  and  use  of  moving  picture  ma- 
chines, scenery  and  other  apparatus  used  in  such  buildings. 

Laws    1916;   Ch.   276. 

§  1.  A  portable  booth  may  be  used  for  temporary  one  night 
exhibitions  of  moving  pictures  in  places  of  publio  assemblage 
in  such  halls  and  buildings  as  are  used  by  commercial  and  fra- 
ternal organizations,  churches,  schools,  and  civic  societies  and 
social  clubs  where  by  reason  of  the  temporary  nature  of  the 
entertainment  it  is  deemed  impracticable  to  install  a  permanent 
booth;  provided,  however,  that  no  portable  booth  shall  be  used 
or  permitted  where  entertainments  last  over  three  nights  in  suc- 
cession. 

§  2.  Such  portable  booth  shall  conform  strictly  to  the  fol- 
lowing1 specifications:  Each  portable  booth  shall  be  at  least  6 
feet  in  height,  inside  measurements.  If  for  the  use  of  one 
picture  machine,  the  area  occupied  by  such  machine  shall  be  not 
less  than  20  square  feet,  and  20  additional  square  feet  for  each 
additional  picture  machine  to  be  operated  therein;  such  portable 
booth  shall  be  constructed  with  the  framework  of  angle  iron 
not  less  than  1%  inches  by  1%  inches  and  3/16  of  an  inch 
thick;  the  iron  members  of  such  framework  shall  be  spaced  not 
more  than  4  feet  apart  on  the  sides,  and  not  more  than  3  feet 
apart  on  the  front,  back  and  top  of  such  portable  booth,  and 
shall  be  enclosed  and  completely  covered  on  all  sides,  top  and 


MOTION     PICTURE     PROJECTION  487 


bottom,  with  either  twenty-four  gauge  steel  plate  or  one-quarter 
inch  asbestos  boards,  excepting  that  if  the  bottom  is  covered 
by  asbestos  boards  said  boards  shall  be  at  least  %  of  an  inch 
thick.  The  floor  of  such  portable  booth  shall  be  elevated  above 
the  permanent  support  on  which  it  is  placed  by  a  space  of  at 
least  %  inch.  Each  portable  booth  shall  be  provided  with  self- 
closing  doors  not  less  than  two  feet  in  width  and  5  feet  and  10 
inches  in  height,  consisting  of  an  angle  iron  frame  covered  with 
either  24  gauge  steel  plate  or  one-quarter  inch  asbestos  board, 
and  attached  to  the  framework  of  such  portable  booth  by  hinges, 
in  such  manner  that  the  door  shall  be  kept  closed  automatically 
at  all  times,  when  not  used  for  ingress  or  egress.  The  windows 
in  such  portable  booth  used  in  connection  with  the  machines 
and  apparatus,  and  by  the  operators  thereof,  shall  not  be  larger 
than  is  reasonably  necessary  to  secure  the  desired  service. 
Twenty-four  gauge  steel  plate  or  14  inch  asbestos  board  shall  be 
provided  for  each  window,  and  shall  be  suspended  and  arranged 
that  they  will  automatically  close  the  window  openings  upon 
the  operation  of  either  a  fusible  or  mechanical  releasing  device, 
with  a  fusible  link  attached;  and  so  far  as  possible  the  con- 
struction of  said  portable  booth  must  meet  the  requirements 
and  specifications  for  a  permanent  booth.  Such  portable  booth 
may  be  constructed  of  a  folding  type,  but  in  such  case  it  must 
be  constructed  in  such  manner  that  when  it  is  assembled  for 
use  it  will  be  rigid  with  all  its  joints  tight. 

Laws  1911;  Ch.  143. 

§  2.  Any  person  having  the  management  or  control  of  any 
theatre  or  place  wherein  theatrical,  acrobatic  or  vaudeville  per- 
formances are  given  by  paid  performers,  or  wherein  any  moving 
picture  show  is  given,  his  agents  or  servants,  who  shall  admit 
thereto,  or  permit  or  suifer  to  remain  therein  any  child  under 
the  age  of  sixteen  years,  unaccompanied  by  a  parent,  guardian 
or  adult  friend,  shall  be  guilty  of  a  misdemeanor  and  punished 
by  a  fine  not  exceeding  one  hundred  dollars. 

Supplement  to  "An  Act  relating  to  regulating  and  providing 
for  the  government  of  cities."  Laws  1902;  Ch.  107. 

Laws  1912;  Ch.  331. 

§  1.  Every  city  of  this  state  which  has  adopted  or  which  may 
hereafter  adopt  the  act  to  which  this  is  a  supplement  shall  have 
power  by  ordinance  to  provide  regulations  for  operating  cine- 
matographs or  moving  picture  machines  and  other  similar  ap- 
paratus, involving  the  use  of  a  combustible  film  more  than  10 
inches  in  length,  and  any  such  city  shall  have  power  by  ordi- 
nance to  provide  for  and  require  examination  by  such  official 
of  said  city  "as  the  governing  body  thereof  shall  select"  of  any 


488  MOTION     PICTURE     PROJECTION 

and  all  persons  over  eighteen  years  of  age  desiring  to  act  as 
operators  of  such  machines  and  to  authorize  such  official  to  issue 
a  license  annually  to  such  person  or  persons  as  shall  success- 
fully pass  an  examination  conducted  under  rules  and  regula- 
tions to  be  approved  by  the  governing  body  of  any  such  city. 
Such  ordinance  may  provide  for  a  fee  to  be  paid  by  every  per- 
son to  whom  a  license  or  renewal  shall  be  issued  and  a  penalty 
for  operating  any  such  machine  without  having  such  license 
therefore  and  for  violation  of  other  terms  and  provisions  of 
such  ordinance,  in  any  amount  not  exceeding  $50  for  each 
offense  or  imprisonment  not  exceeding  30  days  in  default  of  the 
payment  of  such  fine. 

Laws  1917;  Ch.  134. 

§  1.  No  licensed  operator  or  booth  shall  be  required  for  any 
motion  picture  exhibition  in  which  the  apparatus  for  projecting 
such  motion  pictures  uses  only  an  enclosed  incandescent  lamp; 
and  only  cellulose  acetate  or  other  slow  burning  films  of  a  size 
or  perforation  differing  from  the  standard  as  used  in  regularly 
licensed  theatres,  moving  picture  theatres  or  similar  establish- 
ments, providing  such  exhibition  is  approved  by  the  municipal 
authorities  having  jurisdiction. 

Laws  1914;  Ch.  112. 

§  1.  No  operator's  license  shall  be  required  to  operate  any 
cinematograph  or  moving  picture  machine  or  other  similar  ap- 
paratus involving  the  use  of  a  film  more  than  10  inches  in  length 
when  such  apparatus  or  machine  uses  only  cellulose  acetate 
films,  or  other  non-explosive  films  not  more  than  100  feet  in 
length  nor  more  than  one  inch  in  width  and  does  not  require 
more  than  500  watts  of  electric  current  to  operate  the  arc. 


MOTION    PICTURE     PROJECTION  489 


MASSACHUSETTS 
Acts  1914;  Ch.  791. 

§  1.  No  cinematograph,  or  similar  apparatus,  involving 
the  use  of  a  combustible  film  more  than  ten  inches  in  length, 
shall  be  kept  or  used  for  the  purpose  of  exhibiting  such 
films  in  or  upon  the  premises  of  a  public  building,  public 
or  private  institution,  schoolhouse,  church,  theatre,  special 
hall,  public  hall,  miscellaneous  hall,  place  of  assemblage,  or 
place  of  public  resort,  until  such  cinematograph  or  similar 
apparatus  has  been  inspected  and  approved  by  an  inspector 
of  the  building  inspection  department  of  the  district  police, 
who  shall  have  placed  thereon  a  numbered  metal  tag;  nor 
until  a  booth,  or  enclosure,  which  has  been  inspected  and 
approved  by  such  an  inspector  and  his  certificate  issued 
therefor,  has  been  provided  for  said  apparatus;  nor  until 
such  precautions  against  fire  as  the  chief  of  the  district  police 
may  specify  have  been  taken  by  the  owner,  user  or  exhibitor 
therefor;  provided,  however,  that  no  such  cinematograph  or 
similar  apparatus  shall  be  operated  with  oxyhydrogen  gas, 
so-called,  or  with  limelight.  In  addition,  in  the  city  of  Boston, 
the  location  of  any  booth  or  enclosure  surrounding  said  ap- 
paratus, shall  be  approved  by  the  building  commissioner,  who 
may  order  such  additional  precautions  against  fire  as  he  may 
deem  necessary. 

§  2.  The  inspectors  of  the  building  inspection  department  of 
the  district  police  are  hereby  empowered  and  directed  to  inspect 
any  cinematograph  or  similar  apparatus  involving  the  use  of  a 
combustible  film  more  than  ten  inches  in  length,  which  is  to  be 
kept  or  used  in  or  upon  any  of  the  premises  defined  in  section 
one  of  this  act;  and  also  to  inspect  any  booth  or  enclosure  pro- 
vided for  the  same;  and  the  chief  of  the  district  police  shall 
make  such  rules  and  regulations  as  he  may  deem  necessary  for 
the  safe  use  thereof. 

§  3.  For  the  inspection  of  a  cinematograph  or  similar  ap- 
paratus, or  for  the  inspection  of  a  booth  or  enclosure,  as  pro- 
vided by  section  1  of  this  act,  a  fee  of  two  dollars  shall  be 
paid  by  the  owner  or  user  thereof. 

§  4.  Except  as  provided  for  in  section  6  of  this  act,  no  per- 
son shall  exhibit  or  operate  any  cinematograph  or  similar  ap- 
paratus involving  the  use  of  a  combustible  film  more  than  ten 
inches  in  length,  in  or  upon  any  of  the  premises  defined  in 
section  1  of  this  act,  until  he  has  received  a  special  or  first-class 
license  so  to  do  from  an  inspector  of  the  building  inspection 


490  MOTION     PICTURE     PROJECTION 


department  of  the  district  police.  No  such  license  shall  be 
granted  until  the  applicant  has  passed  an  examination  proving 
him  to  be  thoroughly  skilled  in  the  working  of  the  mechanical 
and  electrical  apparatus  or  devices  used  in,  or  connected  with, 
the  operation  of  a  cinematograph  or  similar  apparatus,  as  here- 
inbefore defined,  and  no  person  under  twenty-one  years  of  age 
shall  be  eligible  for  such  examination.  The  fee  for  the  exam- 
ination shall  be  three  dollars  and  shall  accompany  the  applica- 
tion, for  license.  The  first-class  license  shall  be  for  the  term 
of  one  year  from  the  date  thereof,  but  may  be  renewed  yearly 
without  examination,  by  an  inspector  of  the  building  inspection 
department  of  the  district  police,  upon  the  payment  of  a  fee  of 
one  dollar. 

§  5.  Any  person  eighteen  years  of  age  or  over,  desiring  to 
act  as  an  assistant  to  a  holder  of  a  special  or  first-class  license, 
shall  register  his  name,  age  and  address  on  a  form  furnished 
for  the  purpose  by  the  chief  of  the  district  police;  and,  upon 
the  payment  of  a  fee  of  one  dollar,  the  said  chief  may  issue  a 

Sermit  allowing  such  person  to  assist  such  a  licensed  operator 
i  a  booth  or  enclosure;  but  such  person  shall  not  himself 
operate  thi  cinematograph  or  similar  apparatus.  The  permit 
shall  be  for  the  term  of  one  year  from  the  date  thereof,  but  may 
be  renewed  yearly  by  the  chief  of  the  district  police  upon  the 
payment  of  a  fee  of  fifty  cents. 

§  6.  A  second-class  license  giving  the  right  to  operate  a  hand- 
driven  cinematograph  or  similar  apparatus,  but  only  in  the 
presence  of  a  holder  of  a  special  or  first-class  license,  may  be 
granted  to  any  person  who  is  not  less  than  twenty  years  of 
age  and  who  has  been  employed  for  three  months  as  an  assistant 
under  the  supervision  of  a  licensee  or  licensees  in  or  upon  any 
of  the  premises  defined  in  section  1  of  this  act.  The  applicant, 
as  a  condition  of  receiving  the  said  second-class  license,  shall 
pass  an  examination  satisfactory  to  an  inspector  of  the  building 
inspection  department  of  the  district  police,  and  shall  present 
to  the  chief  of  the  district  police  an  affidavit  signed  and  sworn 
to  by  him,  stating  that  he  has  so  worked  for  said  period.  The 
chief  of  the  district  police  may  require  that  the  affidavit  be 
corroborated.  The  fee  for  the  examination  shall  be  two  dollars 
and  shall  accompany  the  application  for  license.  The  license 
shall  be  for  the  term  of  one  year  from  the  date  thereof,  but 
may  be  renewed  yearly  by  an  inspector  of  the  building  inspec- 
tion department  of  the  district  police  upon  the  payment  of  a 
fee  of  fifty  cents. 

§  7.  Any  person  over  twenty-one  years  of  age  who  has  held 
a  second-class  license  for  three  months  or  more  and  has  worked 
regularly  during  that  period  in  a  booth  or  enclosure  in  or  upon 


MOTION     PICTURE     PROJECTION  491 


any  of  the  premises  defined  in  section  1  of  this  act,  may  receive 
a  license  of  the  first  class  upon  presenting  to  the  chief  of  the 
district  police  an  affidavit  signed  and  sworn  to  by  him  stating 
that  he  has  so  worked  for  the  said  period  and  upon  passing  the 
examination  and  payment  of  the  fee  as  provided  for  in  section 
4  of  this  act. 

§  8.  Any  person  who  has  operated  a  cinematograph  or  simi- 
lar apparatus  under  a  license  issued  by  the  district  police  under 
any  preceding  act  and  any  person  over  twenty-one  years  of  age 
who  presents  to  the  chief  of  the  district  police  an  affidavit  signed 
and  sworn  to  by  him  stating  that  he  has  operated  a  cinemato- 
graph or  similar  apparatus  in  a  booth  or  enclosure,  in  a 
theatre  or  hall  devoted  to  public  exhibitions  of  moving  pictures 
outside  the  commonwealth  for  a  period  of  three  months  or  more 
shall  be  eligible  for  the  examination  for  a  special  or  a  first-class 
license  as  provided  in  sections  4  and  10  of  this  act. 

§  9.  A  first-class  license  shall  apply  only  to  the  operation 
of  a  hand-driven  cinematograph  or  similar  apparatus. 

§  10.  The  holder  of  a  first-class  license  as  defined  in  this  act, 
or  any  person  designated  in  section  8  of  this  act  who  passes 
an  examination  satisfactory  to  the  district  police,  may  be 
granted  a  special  license  to  operate  by  hand  or  by  motor  any 
cinematograph  or  similar  apparatus  which  has  been  inspected 
and  tagged  by  the  district  police.  The  fee  for  the  examination 
shall  be  three  dollars  and  shall  accompany  the  application  for  a 
license.  The  license  shall  be  for  the  term  of  one  year  from  the 
date  thereof,  but  may  be  renewed  yearly  by  an  inspector  of  the 
building  inspection  department  of  the  district  police  upon  the 
payment  of  a  fee  of  one  dollar. 

§  11.  An  operator's  license  or  an  assistant's  permit  issued 
under  this  act  may  be  suspended  or  revoked  for  cause  at  any 
time  by  an  inspector  of  the  building  inspection  department  of 
the  district  police,  but  the  person  whose  license  or  permit  is  so 
suspended  or  revoked  may  appeal  to  the  chief  of  the  district 
police,  whose  decision  in  the  matter  shall  be  final. 

§  12.  Except  in  the  city  of  Boston,  the  chief  of  the  district 
police  may  grant  permits  for  the  special  exhibition  of  pictures 
by  the  use  of  a  cinematograph  or  similar  apparatus  in  or  upon 
any  of  the  premises  defined  in  section  1  of  this  act,  which,  in 
his  opinion,  are  in  safe  condition  for  such  exhibitions,  and  he 
may  prescribe  such  regulations  as  he  may  deem  necessary  for 
the  presentation  of  the  same.  A  fee  of  two  dollars  shall  accom- 
pany the  application  for  each  permit. 

§  13.  The  provisions  of  sections  1  to  5,  inclusive,  of  this  act, 
shall  not  apply  to  any  cinematograph  or  similar  apparatus  op- 
erated with  only  cellulose  acetate  films  not  more  than  one  inch 


492  MOTION     PICTURE     PROJECTION 


and  one-fourth  in  width  and  requiring  not  more  than  five  hun- 
dred watts  of  electric  current  to  operate  the  arc ;  provided,  how- 
ever, that  such  machines  shall  not  be  kept  or  used  in  or  upon 
any  of  the  premises  defined  in  section  1  of  this  act  except  under 
such  regulations  as  the  chief  of  the  district  police  shall  pre- 
scribe. 

§  14.  This  act  shall  not  apply  to  licenses  or  special  licenses 
to  operate  cinematographs  or  similar  apparatus  issued  by  the 
district  police  and  now  in  force,  but  upon  the  expiration  of 
any  such  licenses  the  holder  of  a  special  license  shall  be  entitled 
to  a  special  license  under  this  act  upon  the  payment  of  the 
renewal  fee  as  provided  for  in  section  10,  and  the  holder  of  a 
license  shall  be  entitled  to  a  first-class  license  under  this  act 
upon  the  payment  of  the  renewal  fee  as  provided  in  section  4 
of  this  act. 

§  15.  Any  person,  firm,  corporation  or  association  of  per- 
sons, keeping  or  using  a  cinematograph  or  similar  apparatus 
contrary  to  the  provisions  hereof,  or  in  violation  of  any  rule  or 
regulation  made  by  the  chief  of  the  district  police,  or,  in  the 
city  of  Boston,  in  violation  of  any  regulation  or  requirement 
made  by  the  building  commissioner  in  accordance  with  the  pro- 
visions hereof,  shall  be  punished  by  a  fine  of  not  less  than  fifty 
nor  more  than  five  hundred  dollars. 

§  16.  Chapters  five  hundred  and  sixty-five  and  five  hundred 
and  sixty-six  of  the  acts  of  the  year  nineteen  hundred  and 
eight;  chapter  two  hundred  andl  eighty-one  of  the  acts  of  the 
year  nineteen  hundred  and  nine;  chapters  forty-eight  and  four 
hundred  and  forty  of  the  acts  of  the  year  nineteen  hundred  and 
eleven;  chapter  one  hundred  and  eighty-two  of  the  acts  of  the 
year  nineteen  hundred  and  twelve,  and  all  acts  and  parts  of 
acts  inconsistent  herewith  are  hereby  repealed. 

§  17.  Notwithstanding  any  of  the  provisions  of  this  act,  the 
chief  of  the  district  police  may  grant  special  licenses  for  oper- 
ators of  moving  pictures  in  churches,  schoolhouses,  or  public 
institutions  in  the  cities  and  towns  of  the  commonwealth,  except 
Boston,  which,  in  his  opinion,  are  in  safe  condition  for  said 
exhibitions,  and  he  may  prescribe  regulations  for  the  proper 
conduct  of  the  same.  A  fee  of  two  dollars  shall  accompany 
each  application  for  such  special  license.  (Approved  July  7, 
1914.) 


MOTION     PICTURE     PROJECTION  493 


REGULATIONS  GOVERNING  THE  TRANSPORTATION 
OF  INFLAMMABLE  MOTION  PICTURE  FILMS 

Section  246  of  Article  20  of  Chapter  10  of  the  Code  of  Ordi- 
nances : 

"No  person  shall  transport  inflammable  motion  picture  films 
in  any  underground  subway  train,  or  carry  the  same  into  any 
underground  subway  station,  provided,  however,  that  the  pro- 
visions of  this  paragraph  shall  not  apply  to  inflammable  films 
transported  in  the  course  of  interstate  commerce  in  railway 
baggage  or  express  cars  under  the  jurisdiction  and  subject  to 
the  regulations  of  the  interstate  commerce  commission.  No 
person  shall  transport  inflammable  motion  picture  films  in  any 
street  car,  elevated  train,  omnibus,  ferryboat  or  other  public 
conveyance,  or  carry  the  same  into  any  railway  station  or  ferry- 
house  unless  each  film  shall  be  separately  enclosed  in  a  tightly 
closed  metal  box.  Not  more  than  8  films  so  enclosed  shall  be 
carried  at  one  time  by  any  person." 

Adopted  by  the  Board  of  Aldermen,  June  8,  1915,  and 

Effective  June  22,  1915. 


494  MOTIONT     PICTURE     PROJECTION 


QUESTIONS  AND  ANSWERS 

Ques.    What  is  a  gramme? 

Ans.  Unit  of  weight,  the  weight  of  a  cubic  centi- 
meter of  water  at  a  temperature  of  4  degrees  centi- 
grade. 

Ques.    What  is  a  centimeter? 

Ans.  The  unit  of  length,  one  thousandth  millionth 
part  of  a  quadrant  of  the  earth's  surface. 

Ques.    What  is  a  coulomb? 

Ans.  Unit  of  quantity — quantity  of  current  which, 
impelled  by  one  volt  would  pass  through  one  ohm  in 
one  second. 

Ques.    What  is  a  joule? 

Ans.  The  unit  of  work,  the  work  done  by  one  watt 
in  one  second. 

Ques.    What  is  a  circular  mil  ? 

Ans.  A  unit  of  area,  a  mil  is  one  thousandth  part 
of  an  inch,  and  a  circular  mil  is  the  area  of  a  circle 
whose  diameter  is  one  mil. 

Ques.    What  is  ohms  law? 

Ans.  The  current  in  amperes  is  equal  to  the  elec- 
tric motive  force  in  volts,  divided  by  the  resistance 
in  ohms. 

EXAMPLE.  If  we  had  100  volts  and  4  ohms  re- 
sistance in  our  circuit  we  would  get  the  amperage 
(current)  by  dividing  100  (volts)  by  4  (ohms) 
which  would  equal  25  amperes. 

The  resistance  in  ohms  is  equal  to  the  electric 
motive  force  in  volts,  divided  by  the  current  in  am- 
peres. 

EXAMPLE.     If  we  had  100  volts  and  25  amperes 


MOTION     PICTURE     PROJECTION  495 

then  by  dividing  100  (volts)  by  25  (amperes)  we 
would  get  4  (ohms). 

The  electric  motive  force  is  equal  to  the  current  in 
amperes  multiplied  by  the  resistance  in  ohms. 

EXAMPLE.  If  we  had  25  amperes  and  4  ohms 
resistance  and  we  multiplied  them  we  would  get  100 
(volts). 

Ques.  How  would  you  judge  what  size  fuse  you 
would  use  on  your  line? 

Arts.  Take  into  consideration  the  size  of  the  wire 
and  the  amperage  to  be  drawn,  the  fuse  must  be  the 
weakest  part  of  the  circuit. 

Ques.  What  is  meant  by  conductor?  What  is 
generally  used  for  this  purpose? 

Am.  Anything  that  allows  the  passage  of  elec- 
tricity through  it.  Copper. 

Ques.  What  is  the  carrying  capacity  of  a  No.  6 
rubber  covered  wire? 

Ans.    50  amperes. 

Ques.  What  is  the  carrying  capacity  of  a  No.  6 
weatherproof  wire? 

Ans.    65  amperes. 

Ques.  Name  the  three  kinds  of  wire  used  in  moving 
picture  work. 

Ans.  Rubber  covered  wire  for  mains,  asbestos 
covered  wire  for  lamp  leads  used  between  the  table 
switch  and  the  arc  lamp  (wherever  heat  is  generated) 
and  stage  cable  used  for  one  night  stands. 

Ques.  State  if  rubber  covered  wire,  weatherproof 
wire  and  asbestos  wire  are  all  fireproof? 

Ans.  No,  weatherproof  wire  is  moisture  proof 
but  not  fireproof. 


496  MOTION     PICTURE     PROJECTION 

Ques.  What  size  wire  would  you  use  for  your 
mains  for  moving  picture  work? 

Ans.    Size  6  or  larger. 

Ques.  What  size  wire  would  you  use  for  your 
motor  connections  and  what  size  fuse? 

Ans.    Size  14  wire  and  a  6  ampere  fuse. 

Ques.  What  is  the  carrying  capacity  of  a  14 
wire  ? 

Ans.    15  ampres. 

Ques.  On  direct  current  which  wire  would  you 
connect  to  the  top  carbon? 

Ans.    The  positive. 

Ques.  On  which  line,  your  positive  or  negative 
would  you  connect  your  rheostat  ? 

Ans.    On  either  line  it  makes  no  difference. 

Ques.  On  which  line  would  you  connect  a  trans- 
former? 

Ans.  A  transformer  must  be  connected  to  both 
lines  of  a  circuit. 

Ques.    What  is  asbestos  covered  wire? 

Ans.  A  cable  containing  very  fine  strands  of  cop- 
per wires  all  twisted  together  and  the  whole  thing 
covered  with  asbestos. 

Ques.    What  is  rubber  covered  wire? 

Ans.  A  cable  either  solid  or  stranded  covered  with 
a  rubber  covering  and  an  outer  protective  covering 
of  cotton  braid. 

Ques.    What  is  stage  cable? 

Ans.  A  cable  containing  twin  conductors  each 
insulated  from  the  other  and  wrapped  with  a  com- 
position covering. 

Ques.  How  would  you  connect  a  lug  to  one  of  the 
lamp  leads  ? 


MOTION    PICTURE     PROJECTION  497 

Ans.  After  scraping  off  the  asbestos  insulation 
would  insert  cable  into  hole  of  lug  and  would  tighten 
up  with  pliers. 

Ques.    What  is  a  short  circuit? 

Ans.  Two  wires  of  opposite  polarity  coming  in 
contact  with  each  other  without  any  controlling  de- 
vice. 

Ques.  What  is  a  rheostat  and  how  is  it  cons- 
tructed? 

Ans.  An  instrument  used  on  your  line  to  produce 
resistance  and  bring  the  current  to  a  fixed  working 
standard. 

It  is  made  of  a  number  of  metal  coils  or  plates 
(generally  iron  or  German  silver)  connected  in  series 
and  mounted  on  some  insulated  material,  the  whole 
thing  being  enclosed  in  a  metal  cabinet. 

Rheostats  are  made  both  adjustable  and  non- 
adjustable. 

Ques.    Can  you  use  rheostats  on  A.  C.  or  D.  C.  ? 

Ans.  Rheostats  can  be  used  on  both  A.  C.  and 
D.  C.,  but  it  is  cheaper  to  use  an  economizer  or  a 
transformer  instead  of  a  rheostat  on  A.  C. 

Ques.  How  many  rheostats  would  you  use  on  110 
volts? 

Ans.    One  110  volt  rheostat  in  series  on  your  line. 

Ques.  If  automatic  shutter  on  Powers  machine  re- 
fused to  raise  when  machine  started  what  would  you 
do? 

Ans.  Put  a  little  oil  in  oil  hole  in  top  of  move- 
ment ;  if  it  still  refused  to  raise,  would  take  off  casing 
and  see  if  shoes  or  springs  were  caught  or  dirty. 

Ques.    Suppose  the  automatic  shutter  raised  up 


498  MOTION     PICTURE     PROJECTION 

when  machine  started  but  would  not  stay  up  what 
would  you  do? 

Ans.    Put  a  little  heavy  oil  in  movement. 

Ques.  Suppose  the  automatic  shutter  did  not  drop 
when  machine  stopped  how  would  you  fix  it? 

Ans.  Put  a  little  thin  oil  in  movement,  and  if  this 
failed  examine  shoes  and  springs. 

Ques.  What  controls  the  size  of  the  picture  on  the 
screen  ? 

Ans.  The  focal  length  of  the  lens  and  the  distance 
of  machine  from  screen. 

Ques.    What  would  cause  a  travel  ghost  on  screen? 

Ans.    The  flicker  shutter  not  being  adjusted  right. 

Ques.  What  would  happen  if  the  take-up  belt 
refused  to  drive  take-up  or  fell  off  while  the  machine 
was  running? 

Ans.  Film  would  bunch  up  around  lower  sprocket 
and  then  fall  on  floor. 

Ques.  Name  six  revolving  parts  on  the  head  of 
machine  leaving  out  the  sprockets  and  idlers  ? 

Ans.  Flicker  shutter,  balance  wheel,  intermittent 
movement,  centrifugal  movement,  take-up  and  gears. 

Ques.  Name  the  fire  prevention  devices  on  the 
head  of  machine. 

Ans.  Upper  and  lower  magazines,  upper  and 
lower  fire  traps,  upper  and  lower  fire  shields,  auto- 
matic shutter,  cooling  plate. 

Ques.  In  threading  machine  how  would  you  put  in 
film? 

Ans.  Upside  down  and  the  emulsion  side  towards 
lamphouse. 

Ques.  What  comprises  the  optical  system  in  a 
moving  picture  circuit? 


MOTION    PICTURE     PROJECTION  499 

Ans.    The  source  of  light,  condensers  and  lens. 

Ques.    Name  some  of  the  various  kinds  of  lenses. 

Ans.  Double  convex,  double  concave,  piano  con- 
vex, piano  concave,  concavo-convex. 

Ques.  What  is  meant  by  the  back  focal  length  of 
lens? 

Ans.  The  distance  from  the  back  of  the  lens  to 
the  film  in  gate  while  the  picture  is  in  focus  on  screen. 

Ques.    Of  what  use  are  the  condensers  ? 

Ans.  To  bring  the  light  of  arc  lamp  to  a  point  of 
focus  on  aperture  in  gate. 

Ques.  Which  end  of  the  lens  goes  towards  the 
screen? 

Ans.    The  greatest  convex  side. 

Ques.    What  is  meant  by  a  keystone  effect? 

Ans.  When  the  machine  is  set  up  above  the  level 
of  the  screen  and  it  is  necessary  to  tilt  the  machine, 
the  bottom  of  the  picture  will  be  wider  than  the  top, 
owing  to  the  light  rays  having  to  travel  further  to  the 
bottom  of  the  screen  than  to  the  top. 

Ques.     Give  your  definition  of  motion  pictures. 

Ans.  An  optical  illusion  based  on  the  persistence 
of  vision. 

Ques.  What  is  a  fuse,  and  how  many  kinds  are 
there? 

Ans.  A  fuse  is  a  safety  device  used  on  your  line 
to  protect  your  circuit.  Plug  fuses,  cartridge  fuses 
and  link  fuses. 

Ques.  How  many  sets  of  fuses  do  you  use  on  your 
line  for  motion  picture  work  and  what  would  you  call 
them  ? 

Ans.    Two,  main  and  booth  fuses. 


500  MOTION    PICTURE     PROJECTION 

Ques.  What  size  fuse  would  you  use  at  the  main 
and  what  size  at  booth,  using  No.  6  wire? 

Ans.  Fifty  ampere  cartridge  fuse  at  main  and  45 
ampere  link  fuse  in  booth. 

Ques.  Why  not  use  a  45  ampere  cartridge  fuse  in 
booth? 

Ans.  The  department  calls  for  the  use  of  link 
fuses  only ;  the  reason  cartridge  fuses  cannot  be  used 
in  booth  is  that  cartridge  fuses  are  easily  tampered 
with  or  boosted. 

Ques.  Why  do  you  use  a  smaller  size  fuse  in  the 
booth  than  you  do  on  your  mains? 

Ans.  So  that  in  case  of  trouble  the  fuse  in  the 
booth  will  go  first  (it  being  the  weakest  part  of  the 
circuit)  and  you  will  not  have  to  run  down  to  main 
fuses  in  cellar,  as  you  would  have  to  do  if  main  fuses 
were  to  blow. 

Ques.    How  would  you  install  a  link  fuse? 

Ans.  On  a  slate  base  in  a  metal  cabinet  fitted  with 
a  self-closing  door. 

Ques.  What  would  happen  on  your  line  if  you  got 
a  short  circuit? 

Ans.    Blow  your  fuses. 

Ques.  Can  you  use  a  60  ampere  cartridge  fuse  on 
your  mains  on  a  No.  6  wire? 

Ans.  No,  as  this  would  be  overf using,  the  carry- 
ing capacity  of  a  No.  6  wire  is  50  amperes,  and  the 
fuses  must  be  the  weakest  part  of  your  circuit. 

Ques.    What  is  an  ampere,  a  volt  and  an  ohm? 

Ans.  The  ampere  is  the  unit  of  current,  the  volt 
is  the  unit  of  electric  motive  force  (or  pressure),  and 
the  ohm  is  the  unit  of  electrical  resistance. 

Ques.    What  is  a  watt? 


MOTION     PICTURE     PROJECTION  501 

Ans.  The  electrical  unit  of  power.  Amperes  times 
volts  equals  watts. 

Ques.    What  is  a  kilowatt? 

Ans.    1,000  watts  equal  one  kilowatt. 

Ques.    How  many  watts  in  one  horse  power? 

Ans.    746  watts  equal  one  horse  power. 

Ques.    What  is  an  ampere-hour? 

Ans.  Current  in  amperes  multiplied  by  time  in 
hours. 

Ques.    What  is  a  second? 

Ans.  The  unit  of  time,  the  time  of  one  swing  of  a 
pendulum  making  86,400  swings  in  a  solar  day. 

Ques.  What  is  meant  by  the  safe  carrying  capac- 
ity of  wires  ? 

Ans.  All  wires  will  heat  when  a  current  of  elec- 
tricity passes  through  them.  The  greater  the  cur- 
rent or  the  smaller  the  wire,  the  greater  will  be  the 
heating  effect.  Large  wires  are  heated  comparatively 
more  than  small  wires  because  the  latter  have  a 
relatively  greater  radiating  surface. 

Ques.  What  parts  of  a  dynamo  are  liable  to  be 
short  circuited? 

Ans.  The  terminals,  brush  holders,  commutator, 
armature  coils  and  field  coils. 

Ques.  Suppose  on  looking  over  your  motor  you 
found  that  there  were  several  ridges  on  the  commu- 
tator, where  would  you  look  for  the  cause? 

Ans.  The  brushes  are  not  set  right  or  the  tension 
of  brushes  on  commutator  is  too  great.* 

Ques.  How  would  you  go  about  setting  a  Simplex 
flicker  shutter? 

Ans.  When  setting  the  shutter,  set  the  framing 
lever  in  center,  move  the  shutter  adjusting  block  to 


502  MOTION     PICTURE     PROJECTION 

a  point  equidistant  between  the  two  pins  by  means 
of  the  knob  on  the  back  of  the  mechanism  facing 
towards  lamphouse.  Four  teeth  on  intermittent 
sprocket  represents  one  full  move  of  one  section  on 
star,  moving  the  sprocket  two  teeth  either  backward 
or  forward  would  mean  center.  Now  adjust  shutter 
as  follows :  On  a  three  wing  shutter  the  center  of  the 
blade  with  the  word  "Simplex"  stamped  on  it  should 
be  on  center  with  the  lens ;  on  a  two  wing  shutter  the 
center  of  either  blade  will  cover  the  lens.  The  posi- 
tion can  best  be  determined  by  the  set  screw  on  the 
spider,  which  should  face  the  operator  in  a  horizontal 
position.  In  setting  shutter  always  keep  as  close  to 
the  lens  as  possible. 

Ques.    What  is  a  D.  C.  to  D.  C.  motor  generator  ? 

Ans.  It  is  a  D.  C.  motor  connected  to  a  D.  C. 
generator,  used  to  give  a  D.  C.  controlled  light  at 
arc,  thereby  doing  away  with  the  use  of  rheostats. 
When  we  take  into  consideration  the  fact  that  a  rheo- 
stat on  110  volt  circuit  wastes  from  35%  to  50%  of 
the  current,  and  on  220  volts,  rheostats  waste  from 
65%  to  75%  it  will  be  easily  seen  why  a  D.  C.  gen- 
erator should  be  installed  in  place  of  rheostats. 

Ques.  Show  by  figures  what  would  be  the  saving 
if  you  installed  a  Hallberg  D.  C.  generator  and  dis- 
carded your  rheostats,  taking  it  for  granted  that 
you  were  drawing  80  amperes  at  the  arc  on  a  110 
volt  circuit.  . 

Ans.  With  rheostats  we  would  be  consuming  110 
volts  times  80  amperes  or  8,800  watts,  while  with 
the  generator  we  would  be  consuming  110  volts 
times  57  amperes  (this  being  the  amount  of  current 
generator  draws  from  line)  or  6,270  watts.  With 


MOTION     PICTURE     PROJECTION  503 

rheostats  we  consume  8,800  watts  per  hour,  while 
with  generator  we  only  consume  6,270  watts  per 
hour,  the  generator  showing  a  saving  of  1,530  watts 
per  hour. 

Ques.  State  what  advantage  a  motor  generator 
has  over  rheostats  aside  from  the  question  of  current 
saving. 

Ans.  You  do  away  with  the  heat  generated  by  the 
rheostats. 

Ques.  What  is  a  Hallberg  4  in  1  automatic  regu- 
lator? 

Ans.  Consists  of  an  adjustable  transformer  with 
separate  line  and  lamp  coils.  The  primary  coil  is 
wound  in  two  sections,  each  section  insulated  from 
the  other.  Each  section  is  wound  for  110  volts.  For 
110  volts  you  connect  the  two  sections  in  multiple 
while  for  220  volts  you  connect  the  two  sections  in 
series.  It  is  used  for  moving  picture  circuits  when 
using  the  mazda  lamp  instead  of  arc.  (See  page 

(?.) 

Ques.    What  is  meant  by  stealing  the  arc  ? 

Ans.  When  two  arcs  are  connected  to  one  source 
of  supply,  as  when  two  arcs  are  connected  to  one  gen- 
erator, and  where  the  striking  of  the  second  arc 
automatically  puts  out  or  draws  from  the  first  arc. 

Ques.  What  is  meant  by  the  strength  of  a  cur- 
rent? 

Ans.  The  quantity  of  electricity  which  flows  past 
any  point  of  the  circuit  in  one  second. 

Ques.  What  is  the  difference  between  a  dynamo 
and  an  alternator? 

Ans.  A  dynamo  generates  D.  C.,  while  an  alter- 
nator generates  A.  C. 


504  MOTION    PICTURE    PROJECTION 

Ques.  Suppose  you  had  one  110  volt  25  ampere 
rheostat  connected  on  a  110  volt  circuit  D.  C.  and 
you  had  one  110  volt  25  ampere  rheostat  connected 
on  a  110  volt  circuit  A.  C.  at  which  arc  would  you 
draw  the  most  amperage  and  why? 

Ans.  On  the  A.  C.  arc  because  with  A.  C.  you  have 
to  feed  the  carbons  closer  together  than  on  D.  C.  and 
that  draws  a  little  more  amperage. 

Ques.    How  does  a  dynamo  create  current? 

Ans.  It  does  not  create  current  but  generates  an 
induced  E.  M.  F.  which  causes  a  current  to  flow 
through  a  circuit. 

Ques.    How  should  a  knife  switch  be  installed? 

Ans.    So  that  gravity  tends  to  open  same. 

Ques.  Is  it  possible  to  reverse  the  rotation  of  a 
motor,  if  so  how? 

Ans.  Yes,  by  reversing  the  current  through  the 
fields  or  the  current  through  the  armature. 

Ques.  What  is  the  difference  between  a  D.  C.  and 
an  A.  C.  rheostat? 

Ans.  Rheostats  are  made  for  either  A.  C.  or  D.  C. 
There  is  no  difference  between  them. 

Ques.  How  many  rheostats  would  you  use  on  220 
volts  and  how  would  you  connect  same? 

Ans.  One  220  volt  rheostat  in  series  with  your  line 
or  two  110  volt  rheostats  in  series  with  each  other 
and  in  series  on  your  line. 

Ques.  With  55  volts  coming  in,  how  many  rheo- 
stats would  you  use,  and  how  would  you  connect 
same  ? 

Ans.  Use  two  110  volt  rheostats  in  multiple  with 
each  other  and  in  series  on  your  line. 


MOTION    PICTURE     PROJECTION  505 

Ques.  What  effect  does  it  have  by  connecting  rheo- 
stats in  multiple  and  rheostats  in  series? 

Ans.  Rheostats  in  series  give  you  the  sum  of  their 
resistance,  for  instance  if  they  each  offered  4  ohms 
resistance  and  we  connected  same  in  series  with  each 
other  we  would  have  8  ohms  resistance  on  our  line.  If 
we  connected  the  same  two  rheostats  in  multiple  we 
would  only  then  have  approximately  2  ohms  resist- 
ance. 

Ques.  Why  don't  they  use  copper  coils  instead  of 
iron  in  a  rheostat? 

Ans.  Because  iron  offers  more  resistance  than 
copper,  copper  being  a  good  conductor. 

Ques.  Is  all  the  resistance  offered  in  your  rheostat  ? 

Ans.  No,  everything  on  your  line  offers  resistance, 
all  substance  offers  resistance  to  the  passage  of 
electricity  through  them,  the  amount  of  resistance 
depending  on  the  substance  and  its  size,  that  is,  on 
its  length  and  cross  section. 

Ques.  Do  metals  offer  more  or  less  resistance  when 
hot? 

Ans.  The  resistance  of  all  metals  increases  with  an 
increase  of  temperature,  while  carbons  and  insulating 
materials  decrease  with  an  increase  of  temperature. 

Ques.  Is  it  possible  to  get  a  short  circuit  in  the 
rheostat? 

Ans.  Yes,  when  the  arc  lamp  is  burning,  as  you 
then  have  two  polarities  in  rheostat. 

Ques.  How  many  kinds  of  current  are  there  and 
state  what  they  are. 

Ans.    Two,  direct  current  and  alternating  current. 

Ques.    What  is  meant  by  direct  current? 

Ans.    Direct  current  is  a  current  that  alwavs  flows 


506  MOTION     PICTURE     PROJECTION 

in  the  same  direction;  always  leaves  the  dynamo 
through  the  positive  pole  and  returns  through  the 
negative  pole. 

Ques.    What  is  alternating  current? 

Ans.  Alternating  current  is  a  current  that  changes 
its  flow  of  direction  so  many  times  a  second.  Each 
part  of  the  circuit  being  so  many  times  positive  and 
so  many  times  negative  every  second. 

Ques.    What  is  current  frequency? 

Ans.  The  number  of  times  alternating  current 
changes  its  flow  of  direction  in  a  second.  (These 
changes  are  called  cycles.) 

Ques.  Which  current  is  the  best  for  moving  pic- 
ture work  and  why? 

Ans.  Direct  current,  gives  a  better  arc,  more  eas- 
ily controlled,  and  is  not  so  noisy  as  A.  C. 

Ques.    Is  it  possible  to  change  A.  C.  into  D.  C.  ? 

Ans.  Yes,  there  are  various  machines  on  the  mar- 
ket for  this  purpose — transverters,  arc  rectifiers  and 
motor  generator  sets. 

Ques.  Suppose  you  had  J10  volts  D.  C.  coming 
into  Jhe  theatre  and  you  had  one  110  volt  rheostat 
on  your  line,  and  then  the  current  was  changed  from 
D.  C.  to  A.  C.  what  changes  would  you  make  on  your 
line  and  state  reasons  why. 

Ans.  Would  take  off  the  rheostat  and  install  an 
economizer  (step-down  transformer)  this  would  give 
me  a  saving  of  about  66%  (makers  claim). 

Ques.  Suppose  you  changed  a  rheostat  for  an 
economizer  on  a  220  volt  line,  would  there  be  a  sav- 
ing? If  so,  about  how  much? 

Ans.    About  80%  (makers  claims). 

Ques.    State  an  easy  way  to  test  whether  you  have 


MOTION     PICTURE     PROJECTION  507 

A.  C.  or  D.  C.  at  arc  lamp,  and  if  you  are  on  D.  C. 

whether  you  are  connected  right  (positive  line  con- 
nected to  top  carbon). 

Ans.  First  strike  the  arc  and  let  it  burn  a  second 
or  two,  then  throw  off  the  switch  and  open  lamphouse 
door,  if  both  carbons  remain  red  for  the  same  length 
of  time  we  have  A.  C.,  but  should  one  carbon  remain 
red  longer  than  the  other  we  have  D.  C.  The  top 
carbon  should  remain  red  longest,  so  if  the  bottom 
remains  red  longer  than  the  top  we  know  that  we  are 
burning  upside  down.  (Positive  line  is  connected  to 
bottom  carbon  instead  of  to  top). 

Ques.    Suppose  you  find  you  are  burning  upside 
down,  where  on  your  line  would  you  make  the  change  ? 
Ans.    At  table  switch,  arc  lamp  or  wall  switch. 

Ques.  Could  you  change  polarity  at  the  rheostat 
if  you  were  burning  upside  down  ? 

Ans.  No,  as  you  have  only  one  polarity  at  the 
rheostat. 

Ques.  What  is  meant  by  constant  current  type  of 
a  current  rectifying  device? 

Ans.  Where  two  arc  lamps  are  connected  to  one 
apparatus  like  a  transverter  or  a  motor  generator, 
and  where  the  voltage  and  not  the  amperage  is 
doubled  when  both  arcs  are  struck.  For  instance,  if 
we  had  one  arc  operating  at  55  volts  and  50  amperes 
and  we  struck  the  second  arc  we  should  then  have 
two  arcs  operating  at  50  amperes  110  volts  (approx- 
imately). 

Ques.    What  is  a  three  wire  system  ? 

Ans.  A  distribution  system  invented  by  Edison, 
where  two  dynamos  are  connected  in  series  and  th<.- 


508  MOTION    PICTURE    PROJECTION 

third  or  neutral  wire  is  taken  from  a  point  common 
to  both  dynamos. 

Ques.  How  many  rheostats  would  you  use  if  you 
were  using  the  two  outside  wires  of  a  three  wire 
system  ? 

Ans.  Two  110  volt  rheostats  in  series  with  each 
other,  as  between  the  outside  wires  we  would  have 
220  volts. 

Ques.  Suppose  you  were  drawing  50  amperes  off 
one  side  of  a  three  wire  system  and  40  amperes  off 
the  other,  how  many  amperes  would  be  flowing  in  the 
neutral  wire? 

Ans.  As  the  amount  of  current  in  the  neutral  wire 
is  the  difference  between  the  amperage  drawn  off 
either  side,  we  would  have  a  flow  of  10  amperes  in  the 
neutral  wire. 

Ques.  Suppose  that  we  were  drawing  45  amperes 
off  either  side  of  a  three  wire  system  what  would  be 
the  amount  of  amperage  flowing  in  the  neutral  wire? 

Ans.  If  we  were  drawing  45  amperes  off  each  side 
of  the  system,  the  system  would  be  balanced  and  there 
would  be  no  flow  of  current  in  the  neutral  wire. 

Ques.  What  are  the  advantages  of  a  three  wire 
system  ? 

Ans.  The  saving  of  copper  is  the  advantage  of 
the  system,  as  by  its  use  the  size  of  the  conductors 
may  be  reduced,  by  increasing  the  pressure  at  which 
the  current  is  transmitted,  without  increasing  the 
voltage  of  the  lamps.  If  for  example  the  neutral 
wire  is  made  the  same  size  as  the  two  outside  wires, 
the  total  weight  of  the  copper  for  the  three  wire 
system  will  be  three-eighths  (  %  )  of  that  required 


MOTION     PICTURE     PROJECTION  509 

for  two  two-wire  systems  for  the  same  load,  distance 
and  percentage  of  loss. 

Ques.  What  are  the  disadvantages  of  a  three-wire 
system  ? 

Ans.  The  system  is  more  complicated,  the  cost  of 
the  switches,  panel  boards,  etc.,  is  increased,  that  the 
system  is  more  subject  to  disturbances,  if  for  example 
the  fuse  on  the  neutral  wire  should  melt,  the  lamps 
on  the  system  might  be  considerably  damaged  in  case 
the  two  sides  of  the  system  were  not  balanced. 

Ques.  Can  you  connect  between  the  positive  and 
neutral  wire  for  moving  picture  work? 

Ans.  Yes,  you  will  then  need  one  110  volt  rheo- 
stat. 

Ques.  Which  wire  on  a  three-wire  system  is 
grounded  ? 

Ans.    The  neutral  wire. 

Ques.  If  we  were  connected  on  the  positive  and 
neutral  wires  of  a  three-wire  system,  and  we  got  a 
ground  on  the  lower  jaw  of  arc  lamp,  would  that 
blow  the  fuse. 

Ans.  No,  all  metal  machines  must  be  grounded, 
and  by  so  doing  the  lamphouse  becomes  the  same 
polarity  as  the  neutral  wire.  Therefore  the  ground 
being  on  lower  jaw  which  is  neutral  and  the  same 
polarity  as  lamphouse,  it  may  not  blow  the  fuse. 

Ques.  What  is  a  transformer,  how  is  it  made  and 
how  does  it  work? 

Ans.  A  transformer  consists  of  two  copper  coils, 
the  primary  and  the  secondary,  and  a  laminated  iron 
core.  The  two  coils  are  insulated  from  one  another 
and  from  the  core.  The  primary  coil  is  connected  to 


510  MOTION    PICTURE     PROJECTION 

the  source  of  supply  and  the  secondary  is  connected 
to  the  lamp.  As  a  matter  of  fact  these  coils  are  each 
usually  made  of  several  sections.  The  voltage  in- 
duced in  the  secondary  coil  is  equal  to  the  voltage 
impressed  on  the  primary  coil  multiplied  by  the  ratio 
of  the  number  of  turns  in  the  secondary  to  the  num- 
ber in  the  primary  coil,  less  a  certain  drop  due  to 
impedance  of  the  coils  and  to  magnetic  leakage. 
This  drop  is  negligible  on  no  load.  Step-up  trans- 
formers are  used  to  raise  the  voltage.  Step-down 
transformers  are  used  to  step  down  the  voltage. 
The  efficiencies  of  transformers  are  high,  varying 
from  94%  to  95  %  at  one-fourth  load  to  98%  at  full 
load  for  sizes  above  25  K.  W. 

The  current  enters  the  transformer  through  the 
primary  coil  and  the  alternations  of  the  current  in 
this  coil  sets  up  a  magnetic  field  in  the  transformer. 
The  secondary  cuts  the  lines  of  magnetic  force  and 
carries  off  a  new  current  to  the  arc  lamp. 

Ques.  Does  a  transformer  change  the  current 
from  A.  C.  to  D.  C.  ?  , 

Ans.  No,  it  gives  off  a  magnetized  A.  C.  current 
to  arc  lamp. 

Ques.  Can  you  use  a  transformer  on  direct  cur- 
rent ? 

Ans.  No. 

Ques.  Why  do  they  make  the  core  of  a  trans- 
former of  a  soft  metal  like  iron,  instead  of  steel? 

Ans.  Because  the  softer  the  metal  the  more  easily 
it  is  to  magnetize  and  it  will  lose  its  magnetism 
quicker  after  the  current  has  been  shut  off. 

Ques.  State  in  one  word  how  an  economizer  or 
transformer  works. 


MOTION     PICTURE     PROJECTION  511 

Ans.    Induction. 

Ques.    What  is  meant  by  induction? 

Ans.  A  charged  body  running  parallel  to  another 
body  (it  being  a  conductor)  tends  to  charge  the 
neighboring  body  without  any  tangible  form  of  con- 
nection. 

Ques.  How  are  the  coils  in  a  transformer  or  econ- 
omizer connected,  in  multiple  or  series  ? 

Ans.  They  are  not  connected,  they  are  insulated 
from  each  other. 

Ques.  What  is  the  difference  between  an  econo- 
mizer, an  inductor  and  a  step-down  transformer? 

Ans.  None,  they  are  all  the  same  and  answer  the 
same  purpose. 

Ques.  Where  on  your  line  would  you  connect  your 
economizer  and  why? 

Ans.  Between  the  table  switch  and  the  arc  lamp, 
so  that  by  pulling  the  table  switch  you  put  the  arc 
and  the  economizer  out  of  commission  at  the  same 
time,  whereas  if  economizer  was  connected  between 
the  table  switch  and  the  wall  switch  it  would  be 
necessary  to  pull  both  switches  or  at  least  pull  wall 
switch  to  put  both  out  of  commission. 

Ques.  How  many  working  parts  are  there  in  a 
transformer? 

Ans.    None. 

Ques.  Where  is  the  difference  between  a  step-up 
and  a  step-down  transformer? 

Ans.    In  the  ratio  of  the  coil  windings. 

Ques.    What  is  a  transverter? 

Ans.  A  motor  generator  set,  an  A.  C.  motor 
connected  to  a  D.  C.  generator  gives  a  D.  C.  current 
at  arc  lamp.  Or  a  D.  C.  motor  connected  to  a  D.  C. 


512  MOTION     PICTURE     PROJECTION 

generator  that  gives  a  controlled  D.  C.  current  at 
arc  lamp. 

Ques.  What  is  a  mercury  arc  rectifier  used  for? 

Ans.  To  change  A.  C.  to  D.  C. 

Ques.  What  is  the  difference  between  a  motor,  a 
motor  generator  and  a  generator? 

Ans.  A  motor  transforms  electrical  into  mechani- 
cal power.  A  generator  transforms  mechanical 
power  into  electrical  power.  A  motor  generator  is  a 
device  consisting  of  a  motor  mechanically  connected 
to  one  or  more  generators. 

Ques.  What  is  the  difference  between  a  starting 
box  and  a  speed  regulator  ? 

Ans.  Motor  starting  rheostats  or  starting  boxes 
are  designed  to  start  a  motor  and  bring  it  gradually 
from  rest  to  full  speed.  They  are  not  intended  to 
regulate  speed  and  must  not  be  used  for  that  pur- 
pose. Failure  to  observe  this  caution  will  result  in 
burning  out  the  resistance  which  in  a  motor  starter 
is  sufficient  to  carry  the  current  for  a  limited  time 
only,  whereas  in  a  speed  regulator,  sufficient  resist- 
ance is  provided  to  carry  the  full  load  current  con- 
tinuously. 

Ques.    What  is  meant  by  self-induction? 

Ans.  A  characteristic  of  alternating  current  cir- 
cuits, where  the  current  tends  to  create  a  counter  E. 
M.  F.  Self-induction  varies  greatly  with  conditions 
depending  upon  the  arrangement  of  the  circuit,  the 
medium  surrounding  the  circuit,  the  devices  or  ap- 
paratus supplied  or  connected  in  the  circuit,  etc. 
For  example,  if  a  coil  having  a  resistance  of  100 
ohms  is  included  in  the  circuit,  a  current  of  one  am- 
pere can  be  passed  through  the  coil  with  an  electric 


MOTION     PICTURE     PROJECTION  513 

pressure  of  100  volts,  if  direct  current  is  used;  while 
it  might  require  a  potential  of  several  hundred  volts 
to  pass  a  current  of  one  ampere  if  alternating  cur- 
rent is  used,  depending  upon  the  number  of  turns  in 
the  coil,  whether  it  is  wound  on  iron  or  some  other 
non-magnetic  material. 

Ques.  State  six  reasons  for  the  film  jumping  on 
the  screen. 

Ans.  Dirt  on  sprockets,  especially  the  intermit- 
tent sprocket,  losing  the  bottom  loop,  not  enough 
tension  in  gate  of  machine,  sprocket  shaft  not  true, 
shaft  bushings  badly  worn,  holes  in  the  films  worn. 

Ques.  Suppose  you  blow  the  fuse  when  you  strike 
the  arc,  where  would  you  look  for  the  trouble? 

Ans.    In  the  rheostat. 

Ques.  Suppose  you  blow  the  fuse  when  you  close 
the  table  switch,  where  would  you  look  for  the 
trouble? 

Ans.    Between  the  table  switch  and  the  arc  lamp. 

Ques.  If  you  strike  the  arc  and  only  get  a  spark 
and  carbons  refuse  to  hold  arc  where  would  you  look 
for  the  trouble? 

Ans.  Loose  connection  or  oxidized  connection  in 
rheostat  or  on  line. 

Ques.  Is  it  possible  to  get  a  fire  on  the  machine,  if- 
so  how? 

Ans.  Yes,  bad  patches  in  film  opening  up  while 
going  through  machine,  torn  sprocket  .holes  on  each 
side  of  film,  take-up  refusing  to  work,  automatic 
shutter  failing  to  work,  film  breaking  in  gate  between 
upper  and  intermittent  sprocket,  dirt  and  pieces  of 
film  gathering  in  film  aperture  in  gate. 


514  MOTION     PICTURE     PRQJECTION 

Ques.  State  what  you  would  use  to  test  for  ground 
or  open  circuit  in  rheostat. 

Ans.    A  bell  set. 

Ques.  How  would  you  test  for  ground  and  how 
for  open  circuit  in  rheostat? 

Ans.  First  test  bell  set  by  connecting  both  ter- 
minals together,  if  you  get  a  ring  then  set  is  all 
right  and  proceed  as  follows :  Place  one  of  the  ter- 
minals of  bell  set  on  the  frame  of  rheostat  and  the 
other  terminal  on  the  first  coil  or  plate  of  rheostat, 
if  you  get  a  ring,  then  rheostat  is  grounded.  If  you 
do  not  get  a  ring  then  rheostat  is  free  from  ground. 
If  grounded,  to  locate  which  plate  or  coil  is  causing 
the  ground,  proceed  as  follows:  Place  terminal  of 
bell  set  on  frame  and  other  terminal  on  first  coil,  if 
you  get  a  ring,  disconnect  first  coil  then  test  the 
second  and  so  on  till  bell  stops  ringing.  As  soon  as 
bell  stops  ringing  it  signifies  that,  the  coil  that  you 
disconnected  last  is  the  coil  that  was  grounded. 

To  test  for  open  circuit,  place  the  terminals  of 
bell  set  on  the  terminals  on  rheostat  and  if  you  get  a 
ring  then  rheostat  is  O.  K. 

Ques.  If  you  were  drawing  30  amperes  on  a  110 
volt  circuit,  how  many  kilowatts  would  you  be  using? 

Ans.  Volts  times  amperage  equals  watts,  so  110X 
30  equals  3,300,  and  as  there  are  1,000  watts  in  a 
kilowatt  that  means  that  we  have  3  3/10  K.  W. 

Ques.  How  would  you  measure  a  No.  6  rubber 
covered  stranded  wire? 

Ans.  First,  scrape  off  the  insulation,  then  measure 
one  of  the  strands  with  a  B.  &  S.  wire  gauge,  we 
would  find  that  this  strand  would  be  a  No.  14,  then 
by  referring  to  the  wire  table  we  would  find  that  a 


MOTION     PICTURE     PROJECTION  515 

14  wire  contains  4,107  circular  mils,  then  we  count 
the  strands  in  the  cable  and  we  find  there  are  seven, 
so  we  multiply  4,107  by  7  which  equals  28,749,  then 
we  again  refer  to  wire  table  to  find  the  nearest  num- 
ber to  28,749  which  is  26,250  and  looking  across  wire 
column  we  find  that  this  is  a  No.  6  wire. 

Ques.  State  how  you  would  test  lamphouse  for 
grounds. 

Ans.  Take  test  lamp  and  after  making  sure  that 
there  was  current  in  the  lamphouse  (by  placing  test 
lamp  terminals  on  carbons)  'would  proceed  as  fol- 
lows :  Would  place  one  terminal  of  test  lamp  on  the 
upper  carbon  and  the  other  terminal  on  lamphouse, 
if  test  lamp  lights,  then  the  lower  jaw  must  be 
grounded,  if  we  do  not  get  a  light  then  lower  jaw  is 
O.  K.  Then  we  place  one  of  the  test  lamp  terminals 
on  the  lower  jaw  or  carbon  and  the  other  terminal 
we  place  on  metal  of  lamphouse,  if  we  get  a  light 
then  the  upper  jaw  is  grounded,  if  we  do  not  get  a 
light  then  the  upper  jaw  is  O.  K.  If  machine  was 
grounded  we  would  of  course  remove  ground  wire 
before  making  the  test  as  above. 

Ques.    Name  three  essential  parts  of  a  dynamo. 

Ans.    Armature,  commutator,  field  coils. 

Ques.    What  is  the  object  of  the  field  magnets? 

Ans.  To  provide  a  field  of  magnetic  lines  of  force 
to  be  cut  by  the  armature  inductors  as  they  revolve 
in  the  field. 

Ques.    What  is  an  armature? 

Ans.  A  collection  of  inductors  mounted  on  a  shaft 
and  arranged  to  rotate  in  a  magnetic  field  with  pro- 
vision for  collecting  the  current  induced  in  the  in- 
ductors. 


516  MOTION     PICTURE     PROJECTION 

A  simple  loop  or  turn  of  wire  may  be  considered  as 
the  simplest  form  of  armature. 

Ques.  What  is  a  commutator? 

Ans.  A  device  for  causing  the  alternating  cur- 
rents generated  in  the  armature  to  flow  in  the  same 
direction  in  the  external  circuit.  It  consists  of  a 
series  of  copper  bars  or  segments  arranged  side  by 
side  forming  a  cylinder  and  insulated  from  each  other 
by  sheets  of  mica. 

Ques.  How  do  armature  and  field  magnets  differ 
in  dynamos  and  alternators? 

Ans.  In  the  dynamo  the  field  magnet  is  the  sta- 
tionary part  and  the  armature  revolves.  While  in 
an  alternator  the  reverse  is  the  case. 

Ques.    Name  five  parts  of  a  dynamo. 

Ans.  Bed  plate,  field  magnets,  armature,  commu- 
tator, brushes. 

Ques.  The  primary  coil  of  a  transformer  is  sup- 
plied with  a  current  of  25  amperes  at  2,000  volts, 
the  pressure  received  from  the  secondary  is  250  volts. 
What  is  the  current  from  the  secondary  coil,  taking 
it  for  granted  that  the  transformer  is  100%  efficient? 

Ans.  Input  equals  output.  Input  is  2,000  times 
25  equals  50,000  watts.  Watts  divided  by  volts  equals 
amperes,  so  50,000  divided  by  250  equals  200.  There- 
fore the  current  from  the  secondary  is  200  amperes. 

Ques.  What  is  the  name  of  the  coil  in  which  the 
current  is  induced? 

Ans.    The  scondary. 

Ques.  What  is  the  proper  rate  of  speed  of  showing 
1,000  feet  of  film? 

Ans.  About  fifteen  to  seventeen  minutes.  Or  about 
sixteen  pictures  to  the  second. 


MOTION     PICTURE     PROJECTION  517 

Ques.  If  the  machine  is  running  at  proper  speed 
(sixteen  pictures  to  the  second)  about  how  long  is 
each  picture  held  on  the  screen? 

Ans.  For  one-sixteenth  part  of  a  second  less  the 
time  it  takes  the  intermittent  sprocket  to  move  the 
film. 

Ques.  Mention  some  of  the  different  makes  of  mov- 
ing picture  machines. 

Ans.  Powers,  Simplex,  Standard,  Motiograph, 
Baird,  Edison,  Lubin,  Pathe,  Kinemacolor,  Cameron. 

Ques.  Which  would  show  the  greater  saving,  a 
D.  C.  economizer  or  rheostats? 

Ans.  The  initial  cost  of  the  D.  C.  economizer 
would  be  greater  than  that  of  rheostats,  but  the 
working  cost  of  the  D.  C.  economizer  would  show  a 
great  saving  over  that  of  the  rheostats. 

Ques.  Why  are  flicker  shutters  made  with  two  or 
three  blades  when  only  the  largest  blade  is  used  to 
cut  off  the  picture  from  screen  while  the  film  is  in 
motion  in  gate  of  machine? 

Ans.  The  second  and  third  blades  are  on  to  equal- 
ize the  light. 

Ques.    What  is  a  wire  gauge? 

Ans.    A  gauge  used  to  measure  wires. 

Ques.  What  is  the  difference  between  Greenfield 
andB.  X.? 

Ans.  Greenfield  is  a  metal  tubing  without  wires 
while  B.  X  is  the  same  tubing  with  wires. 

Ques.  Does  a  transformer  take  any  current  when 
the  switch  on  the  lamp  side  of  same  is  open? 

Ans.    Yes.    A  no-load  passes  through  the  primary. 

Ques.  What  is  meant  by  an  oil-cooled  trans- 
former ? 


518  MOTION     PICTURE     PROJECTION 

Ans.  A  transformer  filled  with  mineral  oil  to  help 
keep  the  transformer  cool,  never  used  on  moving  pic- 
ture work,  the  fire  risk  is  too  great. 

Ques.  What  would  cause  the  breaking  of  a  brand 
new  film  while  passing  through  the  machine,  taking 
it  for  granted  that  the  film  was  handed  to  you  in 
perfect  condition,  and  that  you  had  just  run  some 
six  or  seven  reels  of  film  through  the  machine  without 
mishap  ? 

Ans.  Caused  by  the  emulsion  coming  off  the  new 
film  and  adhering  to  the  tension  bars  in  gate  of 
machine,  which  would  give  undue  tension  to  the  film. 

Ques.  What  is  meant  by  fading  a  picture?  When 
and  how  is  it  done? 

Ans.  Fading  is  done  by  the  gradual  cutting  off  of 
the  light  (either  when  taking  or  projecting  the  pic- 
ture). The  operator  fades  one  reel  into  the  other 
when  changing  from  one  machine  to  the  other.  This 
is  accomplished  by  the  dowsers  on  the  machines,  by 
slowly  closing  one  and  at  the  same  time  slowly  open- 
ing the  other. 

Ques.  On  which  coil  of  an  economizer  is  the  great- 
est wattage? 

Ans.  As  transformers  are  not  100%  efficient  there 
is  a  loss  in  transforming  the  current,  this  loss 
amounts  to  approximately  5%  and  as  the  output 
equals  the  input  less  the  loss,  it  will  mean  that  we 
have  more  wattage  on  the  primary  than  on  the  sec- 
ondary. 

Ques.    What  is  the  inverse  of  resistance? 

Ans.    Conductivity. 

Ques.  State  one  of  the  disadvantages  of  using 
A.  C.  for  motion  picture  work. 


MOTION     PICTURE     PROJECTION  519 

Ans.  Both  carbons  form  a  crater  and  the  arc 
keeps  traveling  around  carbons  making  it  difficult  to 
get  a  good  steady  light  on  screen. 

Ques.  Of  what  use  is  the  field  magnet  in  a  dynamo  ? 

Ans.  To  provide  a  field  of  lines  of  force  to  be  cut 
by  the  armature  inductors. 

Ques.  State  one  of  the  advantages  of  A.  C.  over 
D.  C.  as  far  as  transmission  goes. 

Ans.  Reduces  the- cost  of  transmission  by  using 
high  voltage  and  transformers. 

Ques.    What  is  the  armature? 

Ans.  A  collection  of  inductors  mounted  on  a  shaft 
and  arranged  to  turn  in  a  magnetic  field  for  collect- 
ing the  current  induced  in  the  inductors. 

Ques.    What  is  a  commutator? 

Ans.  A  device  for  causing  the  alternating  cur- 
rents generated  in  the  armature  to  flow  in  the  same 
direction  in  the  external  circuit. 

Ques.    Which  end  of  the  lens  faces  arc? 

Ans.    The  flat  or  lesser  convex  end. 

Ques.  What  would  you  use  to  scrape  off  the  emul- 
sion from  tension  bars? 

Ans.    Copper  or  any  soft  metal. 

Ques.    WThere  is  the  most  luminous  part  of  an  arc  ? 

Ans.    In  the  crater  of  the  positive  carbon. 

Ques.  What  is  the  difference  between  a  D.  C.  con- 
verter and  a  rotary  converter? 

Ans.  A  D.  C.  converter  converts  D.  C.  to  D.  C., 
while  the  rotary  converter  converts  A.  C.  to  D.  C. 

Ques.    What  is  meant  by  a  circuit? 

Ans.    The  path  in  which  the  current  flows. 

Ques.    What  is  a  closed  circuit? 


520  MOTION     PICTURE     PROJECTION 

Ans.  When  all  switches,  etc.,  on  a  line  are  closed 
giving  the  current  a  continuous  path. 

Ques.    What  is  meant  by  insulation? 

Ans.  Some  non-conducting  material  on  or  around 
a  conductor  to  prevent  the  escape  of  current. 

Ques.  Show  by  sketch  how  a  lens  is  set  and  how 
it  works. 

Ans.    See  page  (?) 

Ques.    What  is  a  circuit  breaker? 

Ans.  A  switch  which  opens*  automatically  when 
the  current  or  pressure  exceeds  or  falls  below  a  cer- 
tain fixed  standard. 

Ques.  What  effect  has  it  by  connecting  dynamos 
in  series  and  dynamos  in  multiple? 

Ans.  Dynamos  in  series  increase  the  volts,  dyna- 
mos in  multiple  increase  the  amperes. 

Ques.  Name  a  number  of  good  conductors,  fair 
conductors  and  non-conductors. 

Ans.  Silver,  copper,  mercury  and  aluminum  are 
good  conductors.  Water,  the  body,  and  dry  wood 
are  partial  conductors  and  mica,  slate,  glass  are  non- 
conductors. 

Ques.  Describe  fully  what  is  meant  by  an  electric 
arc. 

Ans.  Suppose  two  carbons  are  connected  in  an 
electric  circuit,  and  the  circuit  closed  by  touching 
the  tips  of  the  carbons  together  (striking  your  arc)  ; 
on  separating  these  carbons  again  the  circuit  will 
not  be  broken,  providing  the  space  between  be  not 
too  great,  but  will  be  maintained  through  the  arc 
formed  at  this  point.  The  current  is  assumed  as 
passing  from  the  upper  carbon  (positive)  to  the 
lower  carbon  (negative).  We  find  in  a  direct  cur- 


MOTION     PICTURE     PROJECTION  521 

rent  arc  that  most  of  the  light  issues  from  the  tip 
of  the  positive  carbon,  and  this  portion  is  called  the 
crater  of  the  arc.  The  lower  carbon  becomes  pointed 
as  the  upper  one  hollows  out  to  form  the  crater.  The 
negative  carbon  is  also  incandescent,  but  not  to  the 
same  extent  as  the  positive.  Between  the  carbons 
there  is  a  band  of  violet  light  (the  arc  proper)  and 
this  is  surro'unded  by  a  luminous  zone  of  a  golden 
yellow  color.  The  carbons  are  worn  away  or  con- 
sumed by  the  passage  of  the  current.  The  positive 
carbon  being  consumed  about  twice  as  quick  as  the 
lower. 

With  alternating  current  the  upper  carbon  be- 
comes positive  and  negative  alternately,  and  there  is 
no  chance  for  a  good  crater  to  be  formed,  both  car- 
bons giving  off  the  same  amount  of  light  and  being 
consumed  at  about  the  same  rate. 

Ques.  What  is  a  voltmeter  used  for  and  how  would 
you  connect  same? 

Ans.  Used  to  measure  the  pressure  or  voltage, 
connected  in  multiple  on  your  line. 

Ques.  What  is  an  ammeter  and  how  is  it  con- 
nected ? 

Ans.  Used  to  measure  the  current  or  amperage, 
connected  in  series  on  the  line. 

Ques.    What  causes  hissing  of  an  electric  arc? 

Ans.  Feeding  carbons  too  close  together,  feeding 
it  a  higher  current  than  that  required  for  the  length 
of  arc  employed. 

Ques.  What  is  the  reason  of  using  a  cored  carbon 
in  the  positive  jaw  of  arc? 

Ans.    To  reduce  the  voltage  required  to  maintain 


522  MOTION     PICTURE     PROJECTION 

the  arc  by  lowering  the  boiling  point  or  the  vaporiz- 
ing temperature  of  the  crater. 

Ques.  State  the  advantages  of  rubber  as  an  in- 
sulator. 

Ans.    It  is  flexible,  fairly  strong  and  waterproof. 

Ques.  Can  you  use  a  bell  set  to  find  ground  in 
lamphouse? 

Ans.  Yes.  Place  one  terminal  of  bell  set  on  upper 
carbon  and  other  terminal  on  lamphouse  frame,  if 
bell  rings  then  the  upper  jaw  is  grounded,  if  no  ring 
then  upper  jaw  is  O.  K.  Then  place  one  terminal 
of  bell  set  on  lower  carbon  and  other  terminal  on 
lamphouse,  if  bell  rings  then  the  lower  jaw  is  ground- 
ed, if  you  do  not  get  a  ring  then  lower  jaw  is  O.  K. 

Ques.  How  often  would  you  test  lamphouse  for 
grounds  ? 

Ans.    Before  show  each  day. 

Ques.  Suppose  you  found  that  either  the  upper 
or  lower  jaw  was  grounded,  where  would  you  first 
look  for  the  trouble? 

Ans.  Probably  the  mica  insulation  has  worked  out 
of  jaws  of  lamp. 

Ques.  State  what  care  you  would  take  of  film 
while  it  is  in  your  charge. 

Ans.  Would  examine  all  film  before  showing,  keep 
each  reel  in  a  metal  box  or  can,  and  keep  all  these 
cans  in  another  metal  box  constructed  without  solder 
and  with  a  self-closing  door. 

Ques.  Name  three  causes  of  sparking  at  your 
motor. 

Ans.  Dirt,  uneven  brushes  and  broken  segment  in 
the  commutator. 


MOTION     PICTURE     PROJECTION  523 

Ques.  Under  what  conditions  can  you  rewind  film 
in  the  booth? 

Ans.  Never  rewind  films  in  booth  while  arc  is 
burning,  or  while  audience  is  in  theatre. 

Ques.  What  would  you  do  in  case  of  fire  in  the 
booth? 

Ans.  Stop  motor  and  switch  off  arc,  drop  the 
booth  shutters,  turn  on  the  house  lights,  notify  man- 
ager and  try  and  extinguish  fire. 

Ques.  What  precautions  would  you  take  the  pre- 
vent fires? 

Ans.  Keep  all  films  in  fireproof  cans,  only  have 
the  film  on  the  way  to  the  machine  exposed  at  any 
time,  keep  booth  free  from  all  pieces  of  film  and  all 
combustible  material,  see  that  take-up  and  automatic 
shutter  work  O.  K.,  keep  lamphouse  free  from  all 
grounds,  keep  all  electrical  connections  tight,  keep 
machine  clean  and  in  good  running  order,  have  a 
bucket  of  water  and  one  of  sand  near  at  hand  in 
booth,  place  all  hot  carbons  into  a  bucket  of  water 
when  you  take  them  from  arc  lamp. 

Ques.  How  would  you  adjust  the  take-up  without 
stopping  the  machine  ? 

Ans.  If  the  belt  was  slipping  would  use  a  little 
rosin  or  tighten  up  the  tension  screw,  or  use  the  idler 
pulley  if  machine  was  equipped  with  one.  If  take- 
up  refused  to  revolve  the  bottom  reel,  would  stop 
machine  and  fix. 

Ques.    Why  do  they  ground  an  all  metal  machine? 

Ans.    For  safety. 

Ques.  How  would  you  find  the  amount  of  resist- 
ance offered  by  any  conductor? 

Ans.    The  resistance  of  any  conductor  is  equal  to 


524  MOTION     PICTURE     PROJECTION 

its  length  in  feet  divided  by  the  area  in  circular  mils 
multiplied  by  the  resistance  per  mil-foot  (which  is 
10.5  ohms). 

Ques.    What  is  the  international  ohm  ? 

Ans.  The  resistance  offered  by  a  column  of  pure 
mercury  106.3  centimeters  in  length  by  one  square 
milimeter  in  cross  section  at  a  temperature  of  zero 
centigrade. 

Ques.  What  percentage  of  light  is  lost  between 
the  arc  lamp  and  the  screen? 

Ans.  Take  the  crater  of  arc  as  100%,  only  33% 
of  this  is  picked  up  by  the  condensers  on  D.  C.  (On 
A.  C.  the  percentage  is  much  less.)  Then  there  is 
a  16%  reflection  loss  (4%  at  each  of  the  four  glass- 
to-air  surfaces  of  condensers)  plus  an  absorption 
loss  of  9%  (absorption  loss  being  reckoned  as.  6% 
per  inch,  and  assuming  the  condenser  combination  to 
have  an  axial  thickness  of  1%  inch)  or,  in  other 
words,  the  light  falling  upon  the  condensers  is  sub- 
jected to  a  reduction  of  25%  in  passing  through 
them.  Thus  only  25.75%  passes  on  to  the  film  being 
projected.  About  50%  of  this  light  will  be  lost 
passing  through  the  film,  so  that  only  12.85%  is 
sent  on  to  projection  lens.  In  its  passage  through 
the  objective  lens  the  light  is  further  reduced  some 
25%  in  intensity  (4%  reflection  loss  at  each  of  the 
six  glass-to-air  surfaces)  therefore  but  9.65% 
emerges  from  lens.  This  is  again  cut  50%  by  the 
flicker  shutter,  leaving  only  4.80%  of  the  original 
amount  emanating  from  arc  lamp  for  the  illumina- 
tion of  the  creen  picture.  Other  factors  such  as  the 
distance  to  screen  and  the  effective  aperture  of  the 
objective  also  enter,  so  this  is  only  a  rough  approxi- 
mation. 


MOTION     PICTURE     PROJECTION  525 

Ques.  What  is  a  six  to  one  intermittent  move- 
ment ? 

Ans.  A  movement  with  which  each  picture  on  the 
film  is  moved  into  place  before  the  aperture  of  the 
projector  in  an  interval  of  time  equal  to  one-sixth  of 
the  period  required  for  a  complete  revolution  of  its 
driving  member  (cam). 

Ques.  Is  both  voltage  and  amperage  used  up  in 
arc  lamp,  or  is  the  voltage  used  up  and  amperage 
returned;  or  is  the  voltage  returned  to  dynamo  and 
amperage  used  up  at  arc? 

A ns.  The  voltage  is  used  up  forcing  the  amperage 
through  the  resistance.  The  amperage  returns  to 
dynamo.  This  can  be  proved  by  connecting  an  am- 
meter in  your  circuit. 

Ques.  What  would  be  the  result  if  you,  lost  your 
bottom  loop? 

Ans.    Film  would  jump  or  break. 


526  MOTION     PICTURE     PROJECTION 

Ques.  What  regulates  the  speed  of  the  reels  in  the 
upper  and  lower  magazines? 

A ns.  The  top  reel  is  regulated  by  film  tension  and 
the  lower  is  regulated  by  the  tension  spring  and  split 
pulley. 

Ques.  Of  what  use  is  the  flicker  shutter  on  head  of 
machine  ? 

Ans.  To  cut  off  the  rays  of  light  from  screen 
while  the  film  is  in  motion  in  gate. 

Ques.  What  causes  the  film  to  remain  stationary 
in  gate  of  machine? 

Ans.    The  intermittent  movement. 

Ques.  What  is  it  that  works  the  automatic  shut- 
ter? 

Ans.    The  centrifugal  movement. 


MOTION     PICTURE     PROJECTION  527 


EXAMINATION  QUESTIONS 

1.  Name    some    of    the    different    lenses    used    in 
moving  picture  work. 

2.  Under  what  conditions  can  you  rewind  film  in 
the  booth? 

3.  To  which  end  of  the  table  switch  (lamp  or  line) 
would  you  connect  the  primary  coil  of  a  transformer? 

4.  How  is  a  transformer  constructed  and  how  does 
it  work? 

5.  How  would  you  judge  what  size  fuse  to  use  on 
a  line? 

6.  How  is  a  rheostat  made,  and  what  is  it  used! 
for? 

7.  Name  three  kinds  of  wires  used  in  moving  pic- 
ture work. 

8.  What  is  meant  by  induction? 

9.  State   the   difference   between   an   auto    trans- 
former and  a  step-down  transformer. 

10.  How  would  you  ground  an  all  metal  machine,, 
and  after  you  have  same  grounded  would  you  expect 
to  get  a  light  with  test  lamp  if  you  connected  it  be- 
tween either  carbon  of  arc  lamp  and  the  lamphouse 
frame  ? 

11.  Name  three  causes  of  sparking  at  your  motor. 

12.  What  would  happen  if  the  neutral  fuse  on  a, 
three-wire  system  was  to  melt,  providing  the  system 
was  balanced? 

13.  Explain  fully  what  is  meant  by  a  D.  C.  econo- 
mizer. 

14.  Show  by  sketch  the  getting  of  a  D.  C.  arc  and 
-a  jaejt-knife  setting. 


MOTION"     PICTURE     PROJECTION 


15.  Which  fuse  would  you  remove  first  on  a  three- 
wire  system  and  give  reason  wh 

16.  Where  is  a  transverter  used  on  A.  C.  or  D.  C.  ? 

17.  What  is  meant  by  stealing  the  arc? 

18.  Is  the  primary  cofl  of  an  economizer  connected 
in  series  or  multiple  on  your  line? 

19.  Is  there  any  difference  in  the  construction  of  a 
step-up  and  a  step-down  transformer,  which  is  used 
for  moving  picture  work? 

20.  Describe  fully  what  regulates  the  speed  of  a 
Powers,  Simplex  and  a  Standard  machine. 

21.  Do  you  get  A.  C.  or  D.  C.  from  the  secondary 
coil  of  a  transformer? 

22.  Does   the   resistance   of   metals   and   carbons 
increase  or  decrease  with  an  increase  of  temperature? 

23.  What  is  a  rectifier  used  for? 

24.  Name  the  fire  prevention  devices  on  the  head 
of  machine. 

25.  What  controls  the  size  of  the  picture  on  the 
screen? 

26.  What    precautions    would    you    take    before 
starting  your  show? 

27.  How  many  sets  of  fuses  would  you  use  on  your 
line  and  what  would  you  call  them? 

28.  Of  what  use  are  the  condensers? 

29.  Suppose  when  you  struck  the  arc  the  fuse 
melted  where  would  you  look  for  the  trouble? 

30.  How  are  the  coils  in  a  transformer  connected, 
in  multiple  or  series? 

31.  What  would  you  do  in  case  of  fire? 

32.  Show  by  sketch  how  a  lens  works  and  how  it 
is  put  together. 


MOTION'     PICTURE     PROJECTION' 


33.  What  is  the  carrying  capacity  of  a  No.  6,  a 
No.  8,  a  No.  14  rubber  covered  wire? 

34.  Name  the  mechanical  and  electrical  safety  de- 
vices on  the  machine  and  on  the  line. 

35.  What  precautions  must  you  take  when  on  a 
three-wire  system? 

36.  Give  an  easy  way  to  test  for  A.  C.  or  D.  C. 

37.  What  is  the  back  focal  length  of  a  lens? 

38.  Name  the  advantages  and  disadvantages  of  a 
three-wire  system.     State  how  a  three-wire  system  is 
obtained. 

39.  What  would  you  use  to  change  D.  C.  to  A.  C.? 
Is  this  ever  done  for  moving  picture  work?     If  so, 
state  when. 

40.  What  is  a  keystone  effect  on  screen? 

41.  What  is  ohms  law? 

42.  What  is  a  converter  and  where  is  it  used? 

43.  What  is  the  difference  in  construction  between 
a  step-down  transformer,  an  economizer,  and  an  in- 
ductor? 

44.  What  is  meant  by  current  frequency?    Do  we 
get  current  frequency  on  D.  C.  ? 

45.  What  is  a  kilowatt,  and  a  circular  mfl? 

46.  Show  by  sketch  two   rheostats  connected  in 
multiple  with  each  other  and  in  series  on  vour  line. 
State  where  you  would  use  them. 

47.  With  two  110  volt  25  ampere  rheostats  con- 
nected in  series,  how  much  resistance  (in  ohms)  will 
they  offer  in  our  circuit  ? 

48.  What  is  an  electric  arc? 

49.  Explain  how  you  would  test  lamphouse    and 
rheostat  for  ground. 


530  MOTION     PICTURE     PROJECTION 

50.  What  size  wire  would  you  use  for  motor  con- 
nections and  what  size  fuse? 

51.  Show  by  sketch  two  machines  connected  to  one 
source  of  supply. 

52.  On  which  line,  positive  or  negative,  would  you 
connect  your  rheostat? 

53.  What    is    the   difference   between    A.  C.    and 
B.C.? 

54.  State  what  combination  of  carbons  you  would 
use  if  you  were  drawing  50  amperes  D.  C. 

55.  Name  the  principal  parts  of  a  dynamo. 

56.  How  do  you  get  the  equivalent   focus   of  a 
lens? 

57.  Explain  what  the  flicker  or  light  shutter  is 
used  for. 

58.  What  is  a  lug? 

59.  Name  six  causes  of  the  film  jumping  on  screen. 

60.  What  is  the  difference  between  a  short  circuit 
and  a  ground? 

61.  State  if  there  would  be  any  saving,  if  you  in- 
stalled an  economizer  in  place  of  a  rheostat  on  110 
volt  A.  C.  circuit. 

62.  State  how  you  would  go  about  measuring  a 
stranded  and  a  solid  wire. 

63.  With  two  110  volt  25  ampere  rheostats  con- 
nected  in   multiple,   how   much   resistance   in   ohms 
would  they  offer  on  our  line? 

64.  Show  by  sketch  a  complete  circuit  from  the 
main  fuses  in  cellar  up  to  arc  lamp,  taking  it  for 
granted  that  you  have  220  volts  D.  C.  to  work  on. 

65.  Show  by   sketch  a   complete   circuit   using  a 
transformer. 

66.  Suppose   the   output   of   a   transformer   was 


MOTION     PICTURE     PROJECTION  531 

2,500  watts,  50  volts,  what  would  be  the  amount  of 
amperage  ? 

67.  If  you  connected  three  110   volt  50   ampere 
rheostats   in  series,   and   connected  them   on   a   220 
source  of  supply  what  approximate  amperage  would 
this  give  you  at  arc  lamp? 

68.  What  would  be  the  ohmic  resistance  of  three 
110  volts  30  ampere  rheostats,  connected  in  series? 

69.  What   is   the  voltage,   if  we   have   4^    ohms 
resistance  on  line  and  are  getting  35  amperes  at  arc 
lamp  ? 

70.  Connected  between  the  neutral  and  positive 
wire  of  a  three-wire  system   and  with  4  2/5   ohms 
resistance  on  circuit,  what  amperage  have  we  at  arc 
lamp  ? 

71.  When  and  how  is  fading  done? 

72.  On  which  coil  of  a  transformer,  the  primary 
or  secondary,  is   the  most  wattage   and   give   your 
reason  for  this. 

73.  State  fully  what  precautions  you  would  take 
so  that  you  could  project  a  picture  free  from  frame- 
ups. 

74.  By  what  would  you  judge  the  proper  rate  of 
speed  in  projecting  pictures,  how  long  should  it  take 
you  to  run  off  a  2,000-foot  reel? 

75.  What  is  the  wattage  on  a  mazda  lamp  used 
for  moving  picture  projection  work? 

76.  How  would  you  measure  a  stranded  wire? 

77.  Name   six  parts  on  a  motor  generator   and 
state  their  uses. 

78.  What   size  fuse  would  you  install  providing 
you  were  connected  up  on  a  220  volt  circuit  and  had 
two  110  volt  25  ampere  rheostats  on  your  line? 


532  MOTION     PICTURE     PROJECTION 

79.  Name  three  causes  of  your  film  breaking. 

80.  What  lubricant  would  you  use  on  the  follow- 
ing parts  of  the  machine?     (a)  Arc  lamp?     (b)  In- 
termittent movement?   (c)  Gears?     (d)  Motor  bear- 
ings? 

81.  Which  would  be   the  cheaper  to   install   and 
which  the  cheapest  as  far  as  operating  cost,  a  D.  C. 
economizer  or  rheostats? 

82.  What  would  cause  the  breaking  of  a  brand 
new  film  while  passing  through  machine?     Is  there 
any  way  to  help  overcome  this? 

83.  What  is  meant  by  a  travel  ghost,  how  would 
you  remedy  same? 

84.  State  the  working  principle  of  a  Powers  in- 
termittent movement. 

85.  Why  are  flicker  shutters  made  with  more  than 
one  blade?  s 

86.  Of  what  use  is  the  loop  setter  and  on  which 
make  of  machine  will  you  find  same? 

87.  Is  it  possible  to  take  out  a  travel  ghost  while 
the  machine  is  in  motion,  if  so  how  would  you  go 
about  it? 

88.  What  is  a  pin  cross  and  where  on  the  machine 
is  it  situated? 

89.  How  should  fuses  be  installed  ? 

90.  State  one  of  the  disadvantages  of  A.  C.  cur- 
rent for  moving  picture  work. 

91.  Is  it  possible  to  use  cored  carbons  on  D.  C.? 

92.  Name  three  good  conductors,  three  fair  con- 
ductors and  three  non-conductors. 

93.  What  is  meant  by  conductivity  ? 

94.  State  how  you  would  repair  a  torn  film. 

95.  How  would  you  determine  the  amount  of  am- 


MOTION     PICTURE     PROJECTION  533 

perage  that  would  flow  over  a  circuit  in  a  given  time? 

96.  What  effect  would  it  have  on  your  rheostat, 
if  you  changed  from  D.  C.  to  A.  C.  ? 

97.  How  would  you  find  the  saving  of  a  D.  C. 
economizer  or  a  motor-generator  set,  over  that  of  a 
rheostat  ? 

98.  Are   there   any    precautions    that    should   be 
taken  with  new  film  to  prevent  the  breaking  of  same 
while  passing  through  the  machine  ? 

99.  Suppose  you  start  the  machine  and  you  find 
lower  reel  is  not  taking  up,  where  would  you  look 
for  the  trouble? 

100.  What  is  meant  by  the  armature?     Does  the 
armature  revolve  in  a  dynamo  and  alternator? 

101.  What  are  the  brushes  in  a  motor  made  of? 

102.  How  are  the  coils  or  plates  of  a  rheostat 
connected,  in  series  or  multiple? 

*  103.  What  is  meant  by  series  connection  and  mul- 
tiple connection? 

104.  Suppose  the  film  broke  while  passing  through 
the  machine,  state  exactly  what  you  would  do. 

105.  Is  an  ammeter  and  voltmeter  connected  in 
series  or  multiple  on  your  line? 

106.  What  is  meant  by  reflection  and  refraction? 

107.  Why  do  we  get  double  the  voltage  and  not 
double  the   amperage,  when   connected  between  the 
two  outside  wires  of  a  three-wire  system? 

108.  What  is  meant  by  chromatic  aberration? 

109.  What  is  a  friction  disc  speed  regulator? 

110.  What  is  an  ampere-hour? 

111.  State  the  uses  of  following  parts  of  the  ma- 
chine : 


534 MOTION     PICTURE     PROJECTION 

(a)   Flicker  shutter  (g)   Fire  traps 

(6)   Balance  wheel  (h)   Framing  device 

(c)  Speed  regulator  (i)   Objective  lens 

(d)  Intermittent  movement  (j)   Condensers 

(e)  Tension  bars  (k)   Dowser 
(/)   Centrifugal  movement  (Z)   Take-up 

112.  State  how  you  would  clean  the  lenses  of  the 
machine,  and  what  you,  would  use  for  this  purpose. 

113.  Why  not  use  a  cartridge  fuse  in  the  booth 
cut  out? 

114.  What   would   be   the   result    supposing   you 
connected  two  110  volt  25  ampere  rheostats  in  mul- 
tiple, on  a  220  volt  circuit? 

115.  What  is  meant  by  a  balanced  circuit? 

116.  How  many  volts  will  a  No.  6  wire  carry? 

117.  What   is   stage   cable,   rubber   covered  wire, 
and  asbestos  wire? 

118.  State  in  your  own  way  how  we  are  deceived 
into  the  belief  of  motion  while  watching  pictures  on 
the  screen. 

119.  What  is  an  achromatic  lens? 

120.  What  is  a  ground?   What  is  a  short  circuit? 

121.  State  how  it  is  possible  to  get  a  fire  on  head 
of  machine. 

122.  Does  a  transformer  change  A.  C.  to  D.  C.? 

123.  How  would  you  go  about  cleaning  the  head 
of  machine?    What  would  you  use  for  this  purpose? 

124.  What  is  meant  by  the  arc  lamp  burning  up- 
side down  ?    How  would  you  remedy  this  ? 

125.  What  is  a  frame-up? 


MOTION     PICTURE     PROJECTION  535 

126.  State  how  an  objective  lens  is  put  together 
and  say  exactly  what  it  does. 

127.  What  is  the  principle  of  the  revolving  shut- 
ter and  how  would  you  time  it? 

128.  What  would  happen  if  a  coil  in  your  rheo- 
state  melted  out? 

129.  Show  by  sketch  two  machines  connected  to 
a  three-wire  system,  using  rheostats,  and  mark  the 
polarity  of  the  wires. 


MOTION     PICTURE     PROJECTION 


(a)  Flicker  shutter  (g)  Fire  traps 

(b)  Balance  wheel  (h)   Framing  device 

(c)  Speed  regulator  (i)   Objective  lens 

(d)  Intermittent  movement  (j)    Condensers 

(e)  Tension  bars  (&)   Dowser 
(/)   Centrifugal  movement  (Z)   Take-up 

112.  State  how  you  would  clean  the  lenses  of  the 
machine,  and  what  you,  would  use  for  this  purpose. 

113.  Why  not  use  a  cartridge  fuse  in  the  booth 
cut  out? 

114.  What   would   be   the   result    supposing   you 
connected  two  110  volt  25  ampere  rheostats  in  mul- 
tiple, on  a  220  volt  circuit? 

115.  What  is  meant  by  a  balanced  circuit? 

116.  How  many  volts  will  a  No.  6  wire  carry? 

117.  What   is   stage   cable,   rubber   covered   wire, 
and  asbestos  wire? 

118.  State  in  your  own  way  how  we  are  deceived 
into  the  belief  of  motion  while  watching  pictures  on 
the  screen. 

119.  What  is  an  achromatic  lens? 

120.  What  is  a  ground?   What  is  a  short  circuit? 

121.  State  how  it  is  possible  to  get  a  fire  on  head 
of  machine. 

122.  Does  a  transformer  change  A.  C.  to  D.  C.  ? 

123.  How  would  you  go  about  cleaning  the  head 
of  machine?    What  would  you  use  for  this  purpose? 

124.  What  is  meant  by  the  arc  lamp  burning  up- 
side down  ?     How  would  you  remedy  this  ? 

125.  What  is  a  frame-up? 


MOTION     PICTURE     PROJECTION  535 

126.  State  how  an  objective  lens  is  put  together 
and  say  exactly  what  it  does. 

127.  What  is  the  principle  of  the  revolving  shut- 
ter and  how  would  you  time  it? 

128.  What  would  happen  if  a  coil  in  your  rheo- 
state  melted  out? 

129.  Show  by  sketch  two  machines  connected  to 
a  three-wire  system,  using  rheostats,  and  mark  the 
polarity  of  the  wires. 


536  MOTION     PICTURE     PROJECTION 


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124  W.  45th  ST.,  N.  Y.  C.  BRYANT  9375 


MOTION     PICTURE     PROJECTION  537 


INDEX 


Aberration,  Chromatic    124 

A.  C.  Compensarc 67 

A.  C.  Compensarc  in  Multiple 72 

A.  C.  to  D.  C.  Compensarc 345 

Achromatic  Lenses    7-124 

Acme  Projector    152 

Adjusting  Mazda  Lamp 279 

Adjusting  Motor  Generators    434 

Adjustments  on  Simplex  Projector 264 

Advantages  of  a  Three- Wire  System 509 

Alternating    Current    7-37 

Ampere    24 

Ampere-Hour    7 

Amperes   to  Candle-Power 462 

Ammeter     7 

Ammeter  Connections   75 

Apparatus  for  Projection  with  Color  Effects 246 

Approximate  Loss  of  Light  Due  to  Lamp  Globes 461 

Arc    232 

Arc  Controls 178 

Arc  Lamp,  Parts  of 325 

Arc  Rectifier    73 

Armature,    Overheating   of 374 

Asbestos-Covered   Wire    7 

Assembling  and  Cleaning  Lenses 137 

Attaching  Simplex  Motor. '.  244 

Auto-Starter    425 

Auto-Transformer    8 

Automatic   Arc   Controls 178 

Automatic  Loop   Setter    203 

Automatic  Shutter     8-208 

B 

Back  Focus 124 

Balcony   Projection   System '. 110 

Ballast  Rheostat 423 

Battery  Polarity 397 

Battery  and  Switchboard  Connections 381 

Bearings,   Overheating   of 376 

Booth  Plan,  Reo  Theatre 92 

Booth  Supply    91 

Browne  and  Sharpe  Wire  Gauge 8 


538  MOTION     PICTURE     PROJECTION 


Nicholas 
Power 

Company 


WILL  C.  SMITH 

General  Manager 


90  GOLD  ST.,  NEW  YORK  CITY 


MOTION     PICTURE     PROJECTION  539 


Cabinet  Panel  and  Field  Rheostat 345 

Calculation  of   Resistance 27 

Capacity  of  Fuse  Wires 461 

Capitol  Theatre   Projection  Room 95 

Carbons 218 

Carbon  Arc    222 

Carbons,  Combination  for  National 222 

Carbons,  Combination  for  Speer 230 

Carbon   Holders    189 

Care  of  Battery    395 

Care  of  Bearings    346 

Cafe  of  Transverter    365 

Care  of  Westinghouse  Generator    437 

Carrying  Capacity  of  Copper  Wires 449 

Cartridge  Fuses    83 

Causes  of  Generator  Troubles 371 

Centimeters  to  Inches 459 

Centrifugal   Movement 208 

Charging   Batteries 389 

Chromatic  Abberation    9-124 

Cleaning  and  Assembling  Lenses 137 

Color  Effect*   for   Projection 246 

Color  of  Light 228 

Commutator  and   Brushes 347 

Compensarc  Connection  for  35  Ampere  Outfit 335 

Compensarc  Connection  for  50  Ampere  Outfit 337 

Compensarcs  in  Multiple , . . .  72 

Complete  Wiring  Diagram  for  Imsco  Set 382 

Compression  Test 409 

Computing  Focal  Length 136 

Concave  Lenses 126 

Condensers    : 10 

Condenser  Mount  and  Holder 187 

Conductors,  To  find  resistance  of 26 

Connecting  up  Mazda  Apparatus 279 

Connection  for  35  Ampere  Lamp  Outfit 335 

Connection  for  50  Ampere  Outfit 337 

Connection  for  D.  C.  Generator 353 

Connection  for  Hallberg   4-in-l    Regulator (>6 

Connection  for  Westinghouse  Motor  Generator 427 

Connection  for  Type  A.  R.   Motor 426 

Connection  for  a  Double  Arc  Transverter  with 

Emergency   System 868 

Connection  of  Motor  End  of  A.  C.  to  D.  C,  Compensarc . .  339 


540  MOTION     PICTURE     PROJECTION 


"A  Better 
Summer  Business" 

This  is  what  we  call  a  book- 
let we  have  issued.  It  will 
prove  mighty  interesting  to  any 
exhibitor.  It  shows  him  how 
easily  he  can  make  his  house 
pay  big  profits  in  hot  weather. 

If  you  want  to  increase  your 
business  during  the  summer, 
you  need  this  booklet. 

We'll  gladly  send  you  a  copy 
— free. 

Just  drop  us  a  postcard. 
And  if  you  are  building 
a  new  theatre,  asfy  m  also 
for  our  Circular  C-1 . 

Monsoon  Cooling  System,  Inc. 

ROOM  201          70  W.  45th  ST.,  NEW  YORK 


MOTION     PICTURE     PROJECTION  641 

Construction  of  A.  C.   Transformer 509 

Control  Switches  for  Motor  Generator 424 

Controlling  Resistance  Device 53 

Conversion   Tables    457 

Convex  Lenses 126 

Cooling  and  Heating  *of  Theatres 167 

Coulomb    10-28 

Current    24 

Curent  Frequency    10-38 

Current  Required  by  Motors 454 

Cycle  of  Operation  in  a  Four-Cycle  Gas  Engine 412 


D 

D.  C.  to  D.  C.  Generator    352 

D.  C.  to  D.  C.  Motor   Generator    Sets 351 

Device  for  Controlling  Resistance 63 

Diagram  of  Connection  for  A.  C.  Compensarcs 70 

Diagram  of  Elementary  Transformer  58 

Diagram  of  Generator    410 

Diffuse  Lighting  Screens ; .  244 

Direct  Current    10 

Discharging  and  Recharging  Batteries 391 

Distance  to  Which  Full  Load  May  be  Carried 464 

Double  Arc  Transverter  Wiring  Diagram 864 

Dynamos    7 ....  332 


E 

Economizer  Connection  64 

Economizer,  Hallberg  61 

Effect  of  Rheostats  in  Series  and  Multiple 505 

Electric  Arc     232 

Electric  Time  System     143 

Electric  Time  System,   Connections   for 148 

Electrical  Apparatus  for  Studios  and  Theatres 414 

Electrical  Energy  in  Mechanical  Units 30 

Electrical  Resistance 41 

Electrical  Terms 7 

Electricity    11-23 

Electro-Motive-Force     24 

Electrolyte 397 

Elementary  Projection  Machine 114 

Elementary  Rheostat    42 

Elementary  Transformer     58 


542 


MOTION     PICTURE     PROJECTION 


"Acme"  Model  14—  A  Semi-portable 


MOVING  PICTURE   PROJECTOR  WITH 
STEREOPTICON  ATTACHMENT 

Here  is  the  universal  machine  —  a  semi-portable  Moving 
Picture  Projector  superior  to  any  other  similar  machine 
ever  made,  and  with  Stereopticon  Attachment  that  makes 
an  unbeatable  combination.  You  can  run  moving  pic- 
tures alone,  or  lantern  slides  alone.  But  its  greatest 
feature  is  its  instant  adaptability  from  one  to  the  other. 
The  only  machine  with  which  you  can  show  SLIDES 
while  changing  reels.  Think  of  the  advantage  of  being 
able  to  show  a  few  slides  (as  next  week's  announcements, 
or  advertising  slides)  and  thereby  hold  the  attention  of 
your  audience  while  you  are  changing  reels.  The  weight 
is  only  50  pounds.  The  dimensions  are  19%  inches  high, 
8%  inches  deep  and  21^  inches  wide. 

Send  for  Catalog  of  this  and  other  "Acme"  Models 

ACME  M.  P.  PROJECTOR  CO.,    1134  W.  Austin  An,  Chicago 


MOTION     PICTURE     PROJECTION  543 


Energy     '  29 

Emergency  Service  M.  P.  Generator 429 

Equivalent    Focus     11-124 

Equivalent  of  Units  of  Lengths 463 

Equivalent  of  Electrical  Energy  in  Mechanical  Units 80 

Even   Tension   Reel 251 

Examination    Questions     527 

Excessive  Speed   of  Motor 211 

Extra  Lamp  for  Mazda  Work 277 


F 

Failure  of  Motor  to  Start 202 

Few  Facts  Concerning  the  Simplex 260 

Film    234 

Film   Speed    20 

Fire  Trap   11 

Flashing  of  Motor 214 

Flexibility  of  Carbon  Arc. 228 

Flexible   Armored   Cable 71 

Floor  Plan,  Single  Floor  Theatre 112 

Focusing  Mirror,  Mazda  Equipment 275 

Fort  Wayne  A.  C.  to  D.  C.  Compensarc 334 

Foundation  for  Motor  Generator 421 

Freezing  Point  of  Electrolyte 396 

Fuses    83 

Fusing  of  Motor  Generator 855 


G 

General  Care  of  Transverter 365 

General  Points  on  Generator 439 

General  Storage  Battery  Data 396 

Generation   of   Electricity 33 

Generator,  Motor   334 

Generator  Troubles,  Causes  and  Remedies _ 371 

Geneva  Intermittent  Movement 263 

Grounds,  Testing   for 85 

Gundlach   Lenses    .  127 


H 

Hallberg  4-in-l  Mazda  Transformer 66 

Hallberg  Economizer     61 


544  MOTION     PICTURE     PROJECTION 


BETTER  LIGHT  — BETTER  DEFINITION 

With    the 

"KEENOLITE" 

Three    Combination    Lense 


FOR  A  BRIGHT,  STEADY  ARC 
"General  Electric  Generators" 

Can't    Be   Beat,   We    Carry   a 
Stock  For  Immediate  Delivery 


INDEPENDENT  LIGHTING  PLANTS  FOR 
MOVIE  THEATRES 

"IMSCO" 

Engine  and  Generating  Sets 


These  Are  But   a  Few   of   the  IMSCO 

Products.    We  Also  Carry  a  Full 

Line  of  Movie  Supplies 

Independent  Movie  Supply  Co.,  Inc. 

W.  H.  RABELL,  President 

729  SEVENTH  AVE.,  NEW  YORK,  N.  Y. 

CATALOGUE  ON  REQUEST 


MOTION     PICTURE     PROJECTION  545 


Head  of  Powers  6  A 202 

Heart  of  the  Simplex 262 

Heating  and  Ventilating  of  Theatres 167 

Hertner  Transverter   364 

Horse  Power 12 

Horse  Power   to   Watts 457 

How  to  Locate  Break  in  Armature 371 

How  to  Measure  Copper  Wire 448 


I 

Ideal  Projection  Room 96 

Impedance 37 

Imsco  32- Volt  Generating  Plant 379 

Inches  to  Millimeters 459 

Incorrect  Speed  of  Motor 211 

Induction 12-58 

Inductor,    Power's    60 

Installation  of  D.  C.  to  D.  C.  Motor  Generator 351 

Installing  Westinghouse  Generator 423 

Instructions  for  Installing  Compensarc    G7 

Instructions  for  Installing  Peerless  Arc  Controllers 181 

Instructions  for  Installing  the  Simplex  Projector 255 

Instructions  for  Operating  the  Acme  Projector 154 

Instructions  for  Setting  Up  Simplex  Mazda  Equipment.  273 

Intermittent  Gear  Ratio 20 

Intermittent  Movement .  192 

Intermittent  Movement  with  Oil-Tight  Casing 199 

International  Cinema  Center  Projection  Room 100 

International  Ohm    25 


Joule,   The    29 


Keen-o-lite  Lens 141 

Keystone  Effect    499 

Kilowatt    18 


548  MOTION     PICTURE     PROJECTION 


The 
Automatic  Arc  Control 


For  use  on  all  makes  of  Projectors 

A  Complete  Automatic  carbon  feeding  device  that  has 
established  a  new  high  standard  of  excellence  in  screen 
illumination  impossible  to  obtain  with  the  hand-fed  arc. 
Will  completely  free  the  operator  from  the  feed  handle 
of  the  projector.  Always  maintains  the  same  volume  of 
light  on  the  screen. 

Write  for  circular 


THE   J.   E.  McAULEY   MFG. 

30-34  N.  Jefferson  St.  Chicago,  111. 


MOTION     PICTURE     PROJECTION  549 

N 
National  Carbon  Combinations..  221 


O 

Objective    14-125 

Ohm 31 

Ohm's  Law   81 

Oiling  System    432 

Oiling  the  Projector 164 

Operating  the  Transverter 364 

Operation  of  Speed  Control I 26T 

Optical  Projection  121 

Overheating  of  Armature    374 

Overheating  of  Generator  Bearings  376 

Overheating  of  Motor  Starter   212 


P 

Parts  Making  Up  the  Transverter 363 

Parts  on  Head  of  Simplex 295 

Pedestal,  Simplex 319 

Peerless  Arc  Controller 178 

Penal  Laws— New  York 477 

Phantom  View  of  Transverter 865 

Picture  Aperture   20 

Plan  of  Projection  Room,  Capitol  Theatre 95 

Plan  of  Single  Machine  Booth 93 

Plug  Fuses   88 

Points  to  Remember     450 

Points  to  Remember  About  Transformers 61 

Portable  Projectors   152 

Position  of  Screen 248 

Power     29 

Power  Required  for  Driving  Fans 458 

Power's  6B  Cameragraph 191 

Power's  Intermittent  Movement    192 

Power's  6B  Take-up   206 

Power's  Inductor   60-62 

Power's  Loop  Setter 203 

Power's  Rheostat    45 

Power's  Type  "E"  Lamphouse  and  Lamp ] .  185 


550  MOTION     PICTURE     PROJECTION 

A  Permanent  Feature 
For  Your  Theatre 


No  theatre  is  complete  in  its 
equipment  without  an  up-to-date 
Cooling  and  Ventilating  System. 

No  up-to-date  theatre  is  com- 
plete without  the  Typhoon 
Cooling  and  Ventilating  System. 

More  than  a  thousand  theatres 
are  already  equipped  with  the 
permanent  feature. 

TYPHOONS 


TYPHOON  FAN  COMPANY 

345  W.  39th  ST.         :-:         NEW  YORK 

1044  Camp  Street  800  South  Olive  Street 

New  Orleans  Los  Angeles,  Calif. 

64  West  Randolph  Street 

Chicago,  111. 


MOTION     PICTURE     PROJECTION  551 


Precaution  Against  Fire 523 

Pressure,  Electric    23 

Principles  of  Optical  Projection 120 

Projection  Angle    20 

Projection  Arc    219 

Projection  Distance     15 

Projection  Layout    Ill 

Projection  Lens    132 

Projection  Lens  Foci    20 

Projection  Lens  Table    138 

Projection  Objectives    21 

Projection  Room    89 

Projection  Room  International  Cinema  Center 100 

Projector  Carbon  Manufacturing  Process 221 


Q 

Quantity,  Energy  and  Power 28 

Questions  and  Answers 494 


R 

Rate  of  Battery  Discharge 392 

Reactance 41 

Rear  View  of  Acme 163 

Recapitulation 466 

Rectifiers     73 

Reel    21 

Reflecting  Power  of  Walls,  etc 461 

Reflection    15-122 

Refraction     15-123 

Regulating  Engine  to  Procure  Proper  Amperage 394 

Regulations  Governing  the  Transportation  of  Inflammable 

Film  , 493 

Reo  Theatre  Booth  Plan 92 

Repairing  Break  in  Armature 371 

Resistance    25-41 

Resitance  Box  41 

Resistance,  Calculation  of 27 

Resistance  Affected  by  Heating 27 

Resistance  Inversely  Proportional  to  Cross-Section 26 

Resistance  Proportional  to  Length 26 


552  MOTION    PICTURE    PROJECTION 

For  New  and  Used 

PROJECTION  MACHINES 

PORTABLE  PROJECTOR 

MOTOR  GENERATORS 

THEATRE  SEATS 

ELECTRICAL  EQUIPMENT 

BOOTHS,  SCREENS 

ETC.  ETC. 

THEATRE  SUPPLY  Co. 

124  WEST  45th  STREET 
NEW  YORK 

Established  1910  BRYANT  9375 


MOTION     PICTURE     PROJECTION  553 


Restoring  Weakened   Cells 401 

Reversing  Motor  Generator 433 

Rewinder,  Simplex  321 

Rewinding  Table    91 

Rheostats    41 

Rheostats  in  Multiple     48 

Rheostats  in  Series    46 

Right  and  Wrong  Way  to  Set  D.  C.  Arc 218 

Robin  Cinema  Time  System 143 

Robin  Multiple  Unit  Rheostats 50 

Robin  Signal  Telegraph  System 229 

Rotary  Converter 370 

Rules  Governing  the  Granting  of  Operator's  License 467 


S 

Screens     239 

Section  of  Carbon  Holders 189 

Series  Connection  Rheostats 46 

Setting  for   National  Carbons 225 

Setting  Mazda  Lamp  in  Holder   274 

Setting  Up   Simplex   Projector. ' 255 

Self  Induction   612 

Short-Circuit    16 

Showing  Effect  of  Arc  Burning  Upside  Down 229 

Showing  Correct  Method  of  Setting  Brushes 348 

Shutter,  Light   16 

Signal  Telegraph  System    229 

Simplex  Adjustments    264 

Simplex  Arc  Lamp    327 

Simplex-Boylan  Even  Tension  Reel 251 

Simplex  Mazda  Equipment  259 

Simplex  Parts,  Head    295 

Simplex  Parts,  Lamphouse    305 

Simplex  Speed  Regulator 315 

Simplex   Take-up    247-307 

Simplex  Type  "B"     266 

Simplex  Type  "S"  Projector 254 

Sixty-Cycle  A.  C.  Current 89 

Size'of  Wires  for  Motors 456 

Spark   Plug    408 

Sparking  Distances  in  Air 458 

Sparking  of  Motor 202 

Specific  Gravity,  Test  of 398 

Specific  Resistance    27 


554  MOTION     PICTURE     PROJECTION 


S.  M.  P.  E. 


To  Keep  Abreast  of  the  Times 

Read  the  Instructive  Technical  Articles 


in 


The  Transactions 

of  the 

Society  of  Motion  Picture 
Engineers 


Issued  Twice  a  Year 


Can  Be  Obtained  From 

L.  E.  BRAGDON     or     WILL  C.  SMITH 
Motion  Picture  News  90  GOLD  STREET 

729  7th  AVENUE  NEW  YORK  CITY 


MOTION     PICTURE     PROJECTION  555 

Speed  Indicator  Attached  to  Powers 146 

Speed  Indicator  Attached  to  Simplex 144 

Speed  Regulator 317 

Speer  Carbons  230 

Spherical  Aberration 123 

Spread  Lighting   Screens 244 

Standard  Rheostat  Dimensions 52 

Standard  Rheostat  Shelf 94 

Starting  a   Motor  Generator 430 

Starting  an   Imsco    Engine 384 

Starting  the  Compensarc 341-355 

Starting  the  Second  Lamp  of  Compensarc 344 

Step-Down   Transformer    57 

Stereopticon    17 

Storage  Battery,  Preparing  for  Service 379 

Striking  the   Arc 221 

Sulphating     . 403 

Switchboards  ..102-104-106 


T 

Table  of  Brightness   per   Candlepower 453 

Table  of  Electrical  Units 460 

Table  of  Resistivities    and    Conductivities 453 

Take-up   207 

Take-up  Pull 21 

Take-up  Powers 206 

Take-up   Simplex    247 

Technical  Description  of  Intermittent  Movement 194 

Test  of  Specific  Gravity 398 

Test  Lamp    19 

Testing  for  Grounds   85 

Testing  Lamphouse   for   Grounds 87 

Testing  Rheostats  for  Grounds 87 

Theory  of  the  Engine 404 

Thirty-two- Volt  Generating  Plant 379 

Threading  the  Simplex  271 

Three  Combination  Lens    141 

Three  ±»hase 18 

Three  Phase  18 

Three  Unit  Motor  Generator 416 


MOTION    PICTURE     PROJECTION 


Howells  Cine  Equipment  Co. 


LET  US  KNOW 
YOUR   WANTS 


Everything 
From 
The 


WE  CAN  FILL 
THEM 


JOSEPH   C.   HORNSTEIN 

General  Manager 


Phone 
BRYANT   7206 


729  Seventh  Avenue,  New  York  City 


MOTION    PICTURE     PROJECTION  557 


Three  Wire  System  76 

To  Set  Light  Shutter 452 

To  Start  a  Motor 431 

Transformer 57 

Transformer  Connections  59 

Transverter     360 

1  ransverter,  Troubles  and  Remedies 367 

Troubles  and  Remedies  of  Transverter 367 

Two  150-Kil.  Generators,  50-Cycle  Induction  Motors 416 

Two  Arcs  to  a  Three-Wire  System 49 

Two  Light  Generator 435 

Two  Phase    18 

Two  Phase  Compensarc  Connection 341 

Type  "E"  Lamp 190 

Type  S.  K.  D.  C.  Motor 427 

Type  S.  K.  Generator   428 


U 

Useful  Equivalents  for  Electric  Heating 465 

Units  of  Length     463 

Units  of  Electrical  Measurement   .  25 


V 

Variable  Speed  Control   267 

Ventilating  and  Heating  of  Theatres 167 

View  of  Capitol  Theatre  Projection  Room ' 96-98 

View  of  Pin  Cross 200 

View  of  Switchboard  for  Imsco  Engine 881 

Voltmeter    19 

Voltmeter  Connections    75 

Volts  Lost  on  Copper  Wire 455 


W 

Watt     .- , . ; 30 

Watts  Consumed  per  Hour  for  Given  Candle  Power 462 

Watts  to  Horsepower 457 

Westinghouse  Generator    421 

Westinghouse  Generator  for  M.  P.  Projector 415 

Westinghouse  Motor  Generator,  General  Information..  421 

Wire  Table 449 


558  MOTION     PICTURE     PROJECTION 


HAFT ONE" 


THE    SCREEN    OF    A    THOUSAND 
ANGLES 

IT  HAS  NO  "FADE-OUT" 

Shows  Uniform  Distribution  of  Light  over 
its  Entire  Surface  Regardless  of  Angles 


Produces  Brilliant  Pictures  Without  Glare 
or  Eye  Strain  and  Shadows  that  are  Rich 
in  Detail.  Its  "Half-Tones"  are  Remarkable 


Folding    and    Rough    Handling    Cause    no 
Injury 

It    is    Absolutely    Opaque    and    May    be 
Washed 


If  You  are  Interested  in  High-Grade  Pro- 
jection Write  for  Sample 


RAVEN  SCREEN  COMPANY 

257  SOUTH  SECOND  AVENUE 
MOUNT  VERNON,  N.  Y. 


MOTION     PICTURE     PROJECTION 


559 


Wiring  for  Mercury    Arc   Rectifier 73 

Wiring  for  Peerless  Arc  Control 182 

Wiring  Diagram  for  Westinghouse    Generator    425 

"     Two   Lamp   Equipment 282 

"     Single  Lamp  Equipment 284 

"     35   Ampere  Outfit 858 

"     50  Ampere  Outfit 854 

"     Arc  Controller    182 

"     Double  Arc  Transverter 364 

Wiring  for  Rotary   Converter 370 

Wiring  for  Single  Lamp  on  A.  C 278 

Wiring  for  Single  Lamp  on  D.  C 280 

Wiring  for  Two  Generator  Control  Switchboard 369 

Wiring  Instructions    for    Transverter 861 

Working  Distance    19 

Working  Operations  of  Loop  Setter 208 

Working  Principle  of  Elementary  Projection  Machine...  113 


560  MOTION     PICTURE     PROJECTION 

INDEX  TO  ADVERTISERS 

Acme  Portable  Machine  Co 542 

B.  F.  Porter 562 

Haftone  Screen 558 

HowelPs  Cine  Equipment 556 

Independent  Movie  Supply  Co 544 

Inter-Ocean  Film  Corp 176, 177 

J.  E.  Robin 562 

James  R.  Cameron 546 

Monsoon  Cooling  System 540 

Motion  Picture  News in 

Nicholas  Power  Co 538 

Peerless  Arc  Control 548 

Screen  Magazine 561 

Simplex  Machine  Co <  !„# 

Society  of  Motion  Picture  Engineers 554 

Speer  Carbon  Co 231 

Theatre  Supply  Co 536,  552 

Typhoon  Fan  Co 550 


/or  Business 


«^«W. 


561 


$10,000.00  REWARD 

Will  be  paid  to  any  person  who  can  prove  that 

B.  F.  PORTER 

did  not  sell  and  install  the  Simplex  Projectors 
in  the 

CAPITOL  THEATRE 

Broadway  at  51st  St.  New  York  City 

Read  the  Capitol  Program 

B.   F.   PORTER 

Exclusive  Equipment 

729  SEVENTH  AVE.       :-:       NEW  YORK  CITY 

Consult  an  Engineer  of  Reputation 

To  plan  the  Projection  System,  Electrical  Work 
and  Booth  Layout  before  building  or  making 
alterations.  Save  hundreds  to  thousands  of  dol- 
lars. Avoid  constant  costly  Reconstruction. 

References    any   architect    or  Broadway   theatre 
of  importance 

"Robin  Cinema  Electric  Speed  Indicator."    The 
original  and  only  accurate  device  to  run  a  per- 
->^re  on  schedule  and  to  allow  perfect  syn- 
ci**~.  ~*  *l*°  ""'sic  with  the  picture. 

Special   Rheostats,   Switchboards,   j.viiui.V-«-  '^**" 
Control  Panels 

Stock  Devices  of  Merit  Only 

"Highest  award  Panama-Pacific  Int'l  Exposition" 

J.    E.    ROBIN 

729  SEVENTH  AVE.       :•:      NEW  YORK  CITY 


562 


The  Finest  Theatres  in 
the  Principal  Cities  Use 

SIMPLEX 

"The  Cheapest  in  the  Long  Ruh" 


JP*^*^  ^^^^•it 

w 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


Mazda  Simplex  Projector 


MADE    AND    GUARANTEED    BY 


317  East  34th  St~  NewTforic 


563 


